Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Methods for improving biomass yield
Field of the Invention
The present invention relates to methods for improving harvestable biomass
yield in
plants
Background to the Invention
The present invention relates generally to the field of molecular biology and
concerns
a method for increasing total harvestable biomass yield in field-grown plants.
More
specifically, the present invention concerns a method for increasing total
harvestable
biomass yield by transfer, through conventional genetics or transgenesis, of a
specific
genomic region which confers enhanced harvestable yield in field-grown plants.
The total biomass produced above-ground by a plant can be harvested and used
as
feedstock for food, forage, bioenergy (including heat and power, transport
biofuels
and biogas), biomaterials and biorefineries.
Total harvestable - biomass yield is calculated according to the plants parts
that
constitute relevant harvestable product, the most precise being the use of
only one part
(e.g. grain) and the most generic when the total above ground biomass is used.
In food crops the most important aspect is the yield in terms of harvestable
edible
portion which ranges from seed, grain and fruits to all types of vegetative
parts for
vegetable and salad crops (e.g. leaves, roots tubers, modified inflorescences
etc). For
forage there may be additional parts of the plant that animals can eat or the
whole
crop may be relevant.
The production of first generation liquid biofuels requires easily accessible
sugars,
starches or oils. As these are present in harvestable food portions, the
relevant total
yield can be calculated according to the relevant edible food portions.
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In contrast, for many other end-uses, all the above ground parts may be
harvested and
utilised - e.g biomass for bioenergy, biomass for advanced generation biofuels
and
biomass for biorefineries. Whether the total plant is harvested with or
without leaves
and with or without flowers depends on the crop and precise end-use function.
Selective breeding has been employed for centuries to improve, or attempt to
improve, phenotypic traits of agronomic and economic interest in plants such
as yield.
Generally speaking, selective breeding involves the selection of individuals
to serve
as parents of the next generation on the basis of one or more phenotypic
traits of
interest. However, such phenotypic selection is frequently complicated by non-
genetic
factors that can impact the phenotype(s) of interest. Non- genetic factors
that can have
such effects include, but are not limited to environmental influences such as
soil type
and quality, rainfall, temperature range, and others.
Variation in agronomic traits falls into two categories: qualitative and
quantitative.
The term "qualitative trait" is used when variation in the trait falls into
discrete
categories. Qualitative variation of this kind is normally under the control
of one or
two genes whose inheritance can be simply monitored in a cross. However, the
majority of traits of interest to breeders, including total harvestable
biomass yield, are
quantitative in nature and are under the control of several genes each of
which may
have an important but small effect on the trait. The effects of each the
genes, which
may act independently or interact with each other in different ways, are
influenced by
the environment. Consequently, harvestable biomass yield is measured. as a
quantitative character and genomic regions that influence yield are referred
to as
quantitative trait loci (QTL).
It can be very difficult to map the genetic loci that contribute to the
expression of
quantitative traits. For QTL analysis the progeny of a given cross may be
analysed
for the trait and each individual assigned a score depending on the phenotype
observed. All the.individuals in the mapping population are then screened
using
molecular markers. Association between markers and the trait scores are
searched for
using software packages. Because of the environmental influence, the mapping
population needs to be as big as possible and large numbers of molecular
markers
need to be used. Moreover, the mapping population should be grown and assessed
at
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more than one site to ensure that robust QTL have been identified. Because of
the
nature of QTL, for a given complex trait such as yield, several QTL may be
identified
in different locations on the genetic map in a single cross. Attention is
focussed on the
QTL which contribute most to the heritable variation that is observed in the
population. If the same QTL come out strongest when the population is grown at
another site, confidence of their importance is gained. By nature, QTL mapping
is a
long term process and very resource intensive.
Summary
This disclosure concerns markers that define alleles of a gene at a
quantitative trait
locus (QTL) associated with improved harvestable biomass yield in crop plants.
Methods for predicting harvestable biomass yield in a crop plant, for example,
by
determining a contribution to harvestable biomass yield by the allele, using
the
disclosed markers is disclosed. Kits for performing such methods also form
part of
the invention. Transgenic crop plants comprising an exogenous gene associated
with
harvestable biomass yield are disclosed. Transgenic crop plants expressing a
recombinant polypeptide associated with harvestable biomass yield also form
part of
the invention.
The present invention relates to Xyldl, Xyld2, Xyld3, Xyld4, Xyld5, Xyld6,
Xyld7,
Xyld8, Xyld9 and XyldlO polynucleotides and polypeptides and homologues
thereof,
in particular, to these genes found in Populus and Salix and homologues
thereof.
Examples of polynucleotides and polypeptides of Xyldl, Xyld2, Xyld3, Xyld4,
Xyld5, Xyld6, Xyld7, Xyld8, Xyld9 and Xyld10 are shown in the Table below:
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opulus Salix Salix alix Salix
polynucleotid lele A Allele A Allele C Allele C
sequence polynucleotid polypeptide polynucleotid polypeptide
sequence sequence a uence a uence
yldl SEQ ID NO.4 SEQ ID NO. 5 SEQ ID NO.
7
yld2 SEQ ID NO.6 SEQ ID NO. 7 SEQ ID NO.
8
yld3 SEQ ID NO. 8 SEQ ID NO.9 SEQ ID NO.
9
yld4 SEQ ID NO. SEQ ID NO. SEQ ID NO. SEQ ID NO. SEQ ID
11 30 12 0.31
yld5 SEQ ID NO.
13
yld6 SEQ ID NO. SEQ ID NO. SEQ ID NO. SEQ ID NO. SEQ ID NO.
14 15 32 16 33
yld7 SEQ ID NO.3 SEQ ID NO.2 SEQ ID NO. 1 SEQ ID NO.
6
yld8 SEQ ID NO. SEQ ID NO. SEQ ID NO. SEQ ID NO. SEQ ID NO.
17 18 34 19 35
yld9 SEQ ID NO. SEQ ID NO. SEQ ID NO. SEQ ID NO. SEQ ID NO.
0 1 36 2 37
yld10 SEQ ID NO. SEQ ID NO. SEQ ID NO. SEQ ID NO. SEQ ID NO.
3 4 38 5 39
Polynucleotides useful in the invention may comprise nucleotide sequences
having at
5 least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 97, 98, 99 or 100% identity to
the Xyldl,
Xyld2, Xyld3, Xyld4, Xyld5, Xyld6, Xyld7, Xyld8, Xyld9 and XyldlO
polynucleotides.
Polypeptides useful in the invention may comprise amino acid sequences having
at
10 least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 97, 98, 99 or 100% identity
to the Xyldl,
Xyld2, Xyld3, Xyld4, XyldS, Xyld6, Xyld7, Xyld8, Xyld9 and XyldlO
polypeptides.
In preferred aspects of the present invention, polynucleotides and
polypeptides of the
Salix allele C genes are provided for use in the invention.
In preferred aspects of the present invention, polynucleotide and polypeptide
sequences of Xyld7, in particular Xyld7 allele C, are provided for use in the
invention.
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According to a first aspect of of the present invention there is provided
Xyldl, Xyld2,
Xyld3, Xyld4, Xyld5, Xyld6, Xyld7, Xyld8, Xyld9 and Xyld10 polynucleotides and
polypeptides.
5 According to another aspect of the present invention there is provided a
method for
predicting harvestable biomass yield in a crop comprising: genotyping a sample
obtained from a crop plant for one or more markers genetically linked to a
polynucleotide sequence having at least 50, 55, 60, 65, 70, 75, 80, 85, 90,
95, 97, 98,
99 or 100% identity to SEQ ID NO 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
14, 15, 16,
17, 18, 19, 20, 21, 22, 23, 24 or 25, whereby the markers individually or
collectively
identify a haplotype associated with yield in a plurality of crop plants and
correlating
the haplotype with the harvested biomass yield.
According to a further aspect of the present invention there is provided a
method for
predicting harvestable biomass yield in a crop comprising: genotyping a sample
obtained from a crop plant for one or more markers genetically linked to a
polynucleotide sequence having at least 50, 55, 60, 65, 70, 75, 80, 85, 90,
95, 97, 98,
99 or 100% identity to a nucleotide sequence encoding the polypeptide of SEQ
ID NO
26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38 or 39, whereby the markers
individually or collectively identify a haplotype associated with yield in a
plurality of
crop plants and correlating the haplotype with the harvested biomass yield.
According to a further aspect of the present invention there is provided a
method for
determining the contribution of an allele to harvestable biomass yield in a
crop,
wherein the allele is an allele of a polynucleotide sequence, said
polynucleotide
sequence having at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 97, 98, 99 or
100%
identity to SEQ ID NO 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
17, 18, 19,
20, 21, 22, 23, 24 or 25, the method comprising: genotyping a sample obtained
from a
crop plant for one or more markers genetically linked to said polynucleotide,
which
markers individually or collectively identify a haplotype correlated with a
contribution to harvestable biomass yield.
According to a further aspect of the present invention there is provided a
method for
determining the contribution of an allele to harvestable biomass yield in a
crop,
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wherein the allele is an allele of a polynucleotide sequence, said
polynucleotide
sequence having at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 97, 98, 99 or
100%
identity to a nucleotide sequence encoding the polypeptide of SEQ ID NO 26,
27, 28,
29, 30, 31, 32, 33, 34, 35, 36, 37, 38 or 39, the method comprising:
genotyping a
sample obtained from a crop plant for one or more markers genetically linked
to said
polynucleotide, which markers individually or collectively identify a
haplotype
correlated with a contribution to harvestable biomass yield.
According to a further aspect of the present invention there is provided a
method of
identifying an allele that is associated with harvestable biomass yield in a
crop
comprising: obtaining a sample from a crop plant; amplifying DNA present in
said
sample and detecting the presence of a polynucleotide sequence having at least
50, 55,
60, 65, 70, 75, 80, 85, 90, 95, 97, 98, 99 or 100% identity to SEQ ID NO 1, 2,
3, 4, 5,
6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25
in the
amplified DNA.
According to a further aspect of the present invention there is provided a
method of
identifying an allele that is associated with harvestable biomass yield in a
crop
comprising: obtaining a sample from a crop plant; amplifying DNA present in
said
sample and detecting the presence of a polynucleotide sequence having at least
50, 55,
60, 65, 70, 75, 80, 85, 90, 95, 97, 98, 99 or 100% identity to a nucleotide
sequence
encoding the polypeptide of SEQ ID NO 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
36, 37,
38 or 39 in the amplified DNA.
According to a further aspect of the present invention there is provided a
method of
selecting a crop by marker assisted selection of an allele associated with
harvestable
biomass yield, wherein said allele is an allele of a polynucleotide sequence,
said
polynucleotide sequence having at least 50, 55, 60, 65, 70, 75, 80, 85, 90,
95, 97, 98,
99 or 100% identity to SEQ ID NO 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
14, 15, 16,
17, 18, 19, 20, 21, 22, 23, 24 or 25, said method comprising: determining the
presence
of one or more markers, which markers are genetically linked to said
polynucleotide.
According to a further aspect of the present invention there is provided a
method of
selecting a crop by marker assisted selection of an allele associated with
harvestable
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biomass yield, wherein said allele is an allele of a polynucleotide sequence,
said
polynucleotide sequence having at least 50, 55, 60, 65, 70, 75, 80, 85, 90,
95, 97, 98,
99 or 100% identity to a nucleotide sequence encoding the polypeptide of SEQ
ID NO
26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38 or 39, said method
comprising:
determining the presence of one or more markers, which markers are genetically
linked to said polynucleotide.
According to a further aspect of the present invention there is provided an
isolated
nucleic acid sequence comprising a marker or plurality of markers associated
with a
QTL associated with harvestable biomass yield in a crop wherein the marker or
plurality of markers are genetically linked to a polynucleotide sequence
having at
least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 97, 98, 99 or 100% identity to
SEQ ID NO
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,
23, 24 or 25.
According to a further aspect of the present invention there is provided an
isolated
nucleic acid sequence comprising a marker or plurality of markers associated
with a
QTL associated with harvestable biomass yield in a crop wherein the marker or
plurality of markers are genetically linked to a polynucleotide sequence
having at
least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 97, 98, 99 or 100% identity to a
nucleotide
sequence encoding the polypeptide of SEQ ID NO 26, 27, 28, 29, 30, 31, 32, 33,
34,
35, 36, 37, 38 or 39.
According to a further aspect of the present invention there is provided a
method for
producing a transgenic crop plant, comprising introducing into an unmodified
crop
plant an exogenous polynucleotide, wherein said polynucleotide comprises a
nucleotide sequence having at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95,
97, 98, 99 or
100% identity to SEQ ID NO 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
16, 17, 18,
19, 20, 21, 22, 23, 24 or 25.
According to a further aspect of the present invention there is provided a
method for
producing a transgenic crop plant, comprising introducing into an unmodified
crop
plant an exogenous polynucleotide, wherein said polynucleotide comprises a
nucleotide sequence having at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95,
97, 98, 99 or
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100% identity to a nucleotide sequence encoding the polypeptide of SEQ ID NO
26,
27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38 or 39.
According to a further aspect of the present invention there is provided a
method for
producing a transgenic crop plant that expresses a recombinant polypeptide
encoded
by a sequence having at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 97, 98,
99 or 100%
identity to SEQ ID NO 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
17, 18, 19,
20, 21, 22, 23, 24 or 25, comprising introducing an exogenous polynucleotide
comprising a cDNA encoding said recombinant polypeptide into an unmodified
crop
plant.
According to a further aspect of the present invention there is provided a
method for
producing a transgenic crop plant that expresses a recombinant polypeptide
comprising an amino acid sequence having at least 50, 55, 60, 65, 70, 75, 80,
85, 90,
95, 97, 98, 99 or 100% identity to SEQ ID NO 26, 27, 28, 29, 30, 31, 32, 33,
34, 35,
comprising introducing an exogenous polynucleotide comprising a cDNA encoding
said recombinant polypeptide into an unmodified crop plant.
According to a further aspect of the present invention there is provided a
transgenic
crop plant comprising an exogenous gene, wherein said gene comprises a
sequence
having at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 97, 98, 99 or 100%
identity to
SEQ ID NO 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
20, 21, 22,
23, 24 or 25.
According to a further aspect of the present invention there is provided a
transgenic
crop plant comprising an exogenous gene, wherein said gene comprises a
sequence
encoding a polypeptide, the polypeptide having at least 50, 55, 60, 65, 70,
75, 80, 85,
90, 95, 97, 98, 99 or 100% identity to the polypeptide of SEQ ID NO 26, 27,
28, 29,
30, 31, 32, 33, 34, 35, 36, 37, 38 or 39.
According to a further aspect of the present invention there is provided a
transgenic
crop plant expressing a recombinant polypeptide encoded by a sequence having
at
least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 97, 98, 99 or 100% identity to
SEQ ID NO
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,
23, 24 or 25.
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According to a further aspect of the present invention there is provided a
transgenic
crop plant expressing a recombinant polypeptide having at least 50, 55, 60,
65, 70, 75,
80, 85, 90, 95, 97, 98, 99 or 100% identity to SEQ ID NO 26, 27, 28, 29, 30,
31, 32,
33, 34, 35, 36, 37, 38 or 39.
According to a further aspect of the present invention there is provided a
transgenic
crop plant comprising a nucleotide sequence having at least 50, 55, 60, 65,
70, 75, 80,
85, 90, 95, 97, 98, 99 or 100% identity to SEQ ID NO 1, 2, 3, 4, 5, 6, 7, 8,
9, 10, 11,
12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25, wherein said
nucleotide
sequence is operably linked to a heterologous regulatory element.
According to a further aspect of the present invention there is provided a
transgenic
crop plant comprising a nucleotide sequence having at least 50, 55, 60, 65,
70, 75, 80,
85, 90, 95, 97, 98, 99 or 100% identity to a nucleotide sequence encoding the
polypeptide of SEQ ID NO 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38 or
39,
wherein said nucleotide sequence is operably linked to a heterologous
regulatory
element.
According to a further aspect of the present invention there is provided a use
of an
exogenous polynucleotide comprising a sequence having at least 50, 55, 60, 65,
70,
75, 80, 85, 90, 95, 97, 98, 99 or 100% identity to SEQ ID NO 1, 2, 3, 4, 5, 6,
7, 8, 9,
10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25 or the
corresponding
cDNA sequence, for improving harvestable biomass yield of a crop plant by
transformation of the crop plant with the exogenous polynucleotide.
According to a further aspect of the present invention there is provided a use
of an
exogenous polynucleotide comprising a sequence having at least 50, 55, 60, 65,
70,
75, 80, 85, 90, 95, 97, 98, 99 or 100% identity to a nucleotide sequence
encoding the
polypeptide of SEQ ID NO 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38 or
39, for
improving harvestable biomass yield of a crop plant by transformation of the
crop
plant with the exogenous polynucleotide.
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According to a further aspect of the present invention there is provided a
genetic
construct comprising (a) a nucleotide sequence having at least 50, 55, 60, 65,
70, 75,
80, 85, 90, 95, 97, 98, 99 or 100% identity to SEQ ID NO 1, 2, 3, 4, 5, 6, 7,
8, 9, 10,
11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25 or the
corresponding cDNA
5 sequence, and (b) a promoter sequence capable of directing expression of the
protein
encoded by the nucleotide sequence in a plant comprising the genetic
construct.
According to a further aspect of the present invention there is provided a
genetic
construct comprising (a) a nucleotide sequence having at least 50, 55, 60, 65,
70, 75,
10 80, 85, 90, 95, 97, 98, 99 or 100% identity to a nucleotide sequence
encoding the
polypeptide of SEQ ID NO 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38 or
39, and
(b) a promoter sequence capable of directing expression of the protein encoded
by the
nucleotide sequence in a plant comprising the genetic construct.
According to a further aspect of the present invention there is provided a
plant
transformation vector comprising the genetic construct of the invention.
According to a further aspect of the present invention there is provided a
plant or plant
cell comprising a transformation vector of the invention.
In one or more embodiments of the invention, the marker is within an interval
of less
than 45, 40, 35, 30, 25, 20,15,10, 5, 4, 3, 2,1 or 0 centimorgans (cM) from a
nucleotide sequence having at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95,
97, 98, 99 or
100% identity to SEQ ID NO 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
16, 17, 18,
19, 20, 21, 22, 23, 24 or 25.
In one or more embodiments of the invention, the marker is within an interval
of less
than 45, 40, 35, 30, 25, 20,15,10, 5, 4, 3, 2,1 or 0 centimorgans (cm) from a
nucleotide sequence having at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95,
97, 98, 99 or
100% identity to a nucleotide sequence encoding the polypeptide of SEQ ID NO
26,
27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38 or 39.
Plants that are particularly useful in the methods of the invention include in
particular
monocotyledonous and dicotyledonous fodder crops, forage crops, ornamental
crops,
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fruit crops, food crops, algae, forestry trees, bioenergy crops and biofuel
crops
including the following species and species hybrids: Acacia spp., Acer spp.,
Actinidia
ssp., Agave spp., Agropyron spp., Agrostis spp., Allium spp., Alnus spp.,
Alopecurus
spp., Amaranthus spp., Ananas spp., Apium spp., Arachis spp., Areca spp.,
Arundo
spp., Arrhenatherum spp., Asparagus spp; Avena spp., Atriplex spp., Attalea
spp.,
Beta spp., Betula spp., Brassica spp., Bromus spp., Bouteloua spp.,Camelina
spp.,
Camellia spp., Cannabis spp., Capsicum spp., Carica spp., Carex spp.,
Carthamus
spp., Castanea spp., Carum spp., Cinnamomum spp., Citrus spp., Cocos spp.,
Coffea
spp., Corchorus spp., Cotoneatser spp., Cucurbita spp., Cupressus spp.,
Cynodon
spp., Daucus spp., Dactylis spp., Eucalyptus spp., Elaeis spp., Eleusine spp.,
Fagus
spp., Festuca spp., Ficus spp., Fraxinus spp., Geranium spp., Ginkgo spp.,
Glycine
spp., Gossypium spp., Helianthus spp., Hemerocallis spp., Heracleum spp.,
Hedysarum spp., Hibiscus spp., Hordeum spp., Indigo spp., Ipomoea spp.,
Lettuca
spp., Jatropha spp., Lotus spp., Lactuca spp., Lathyrus spp., Lens spp., Linum
spp.,
Lolium spp., Lupinus spp., Lezula spp., Lycopersicon spp., Malus spp., Manihot
spp.,
Medicago spp., Melilotus spp., Mentha spp., Miscanthus spp., Musa spp.,
Nicotiana
spp., Olea spp., Onobrychis spp., Ophiopogon spp., Oryza spp., Panicum spp.,
Papaver spp., Petunia spp., Phaseolus spp., Pennisetum spp., Phalaris spp.,
Phoenix
spp., Phleum spp., Phyllostachys spp., Physalis spp., Panicum spp., Picea
spp., Pinus
spp., Pistacia spp., Pisum spp., Poa spp., Podocarpus spp., Pogmania spp.,
Populus
spp., Prunus spp., Quercus spp., Ribes spp., Robinia spp., Rosa spp., Raphanus
spp.,
Rheum spp., Ricinus spp., Rubus spp., Salix spp., Sequoia spp., Sesamum spp.,
Setaria
spp., Saccharum spp., Sambucus spp., Secale spp., Sinapis spp., Solanum spp.,
Sorghum spp., Trifolium spp., Triticum spp., Triticosecale spp., Trisetum
spp.,
Tagetes spp., Theobroma spp., Triadica spp., Vicia spp., Vitis spp., Vigna
spp., Viola
spp., Watsonia spp., Zea spp. amongst others.
According to another aspect of the present invention there is provided a
polypetide
having the amino acid sequence od SEQ ID NO: 1.
The foregoing and other objects and features of the disclosures will become
more
apparent from the following detailed description, which proceeds with
reference to the
accompanying figures.
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Figure 1: shows the sequence of a QTL region in Populus associated with
improved
yield.
Figure 2 shows the sequence of a QTL region in Sal ix associated with improved
yield.
The sequence is derived from allele A.
Figure 3A: shows the nucleotide sequence of the Xyldl polynucleotide of
Populus
(SEQ ID NO 4). SEQ ID NO 4 is located within the QTL region shown in Figure 1.
Figure 3B: shows the nucleotide sequence of the Xyldl allele A polynucleotide
of
Salix (SEQ ID NO 5).
Figure 3C: shows the amino acid sequence of the Xyldl allele A polypeptide of
Salix
(SEQ ID NO 27).
Figure 4A: shows the nucleotide sequence of the Xyld2 polynucleotide of
Populus
(SEQ ID NO 6). SEQ ID NO 6 is located within the QTL region shown in Figure 1.
Figure 4B: shows the nucleotide sequence of the Xyld2 allele A polynucleotide
of
Salix (SEQ ID NO 7).
Figure 4C: shows the amino acid sequence of the Xyld2 allele A polypeptide of
Salix
(SEQ ID NO 28).
Figure 5A: shows the nucleotide sequence of the Xyld3 polynucleotide of
Populus
(SEQ ID NO 8). SEQ ID NO 8 is located within the QTL region shown in Figure 1.
Figure 513: shows the nucleotide sequence of the Xyld3 allele A polynucleotide
of
Salix (SEQ ID NO 9).
Figure 5C: shows the amino acid sequence of the Xyld3 allele A polypeptide of
Salix
(SEQ ID NO 29).
Figure 6A: shows the nucleotide sequence of the Xyld4 polynucleotide of
Populus
(SEQ ID NO 10). SEQ ID NO 10 is located within the QTL region shown in Figure
1.
Figure 6B: shows the nucleotide sequence of the Xyld4 allele A polynucleotide
of
Salix (SEQ ID NO 11).
Figure 6C: shows the nucleotide sequence of the Xyld4 allele C polynucleotide
of
Sal ix (SEQ ID NO 12).
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Figure 6D: shows the amino acid sequence of the Xyld4 allele A polypeptide of
Salix
(SEQ ID NO 30).
Figure 6E: shows the amino acid sequence of the Xyld4 allele C polypeptide of
Salix
(SEQ ID NO 31).
Figure 7: shows the nucleotide sequence of the Xyld5 polynucleotide of Populus
(SEQ ID NO 13). SEQ ID NO 13 is located within the QTL region shown in Figure
1.
Figure 8A: shows the nucleotide sequence of the Xyld6 polynucleotide of
Populus
(SEQ ID NO 14). SEQ ID NO 14 is located within the QTL region shown in Figure
1.
Figure 8B: shows the nucleotide sequence of the Xyld6 allele A polynucleotide
of
Salix (SEQ ID NO 15).
Figure 8C: shows the nucleotide sequence of the Xyld6 allele C polynucleotide
of
Salix (SEQ ID NO 16).
Figure 8D: shows the amino acid sequence of the Xyld6 allele A polypeptide of
Salix
(SEQ ID NO 32).
Figure 8E: shows the amino acid sequence of the Xyld6 allele C polypeptide of
Salix
(SEQ ID NO 33).
Figure 9A: shows the nucleotide sequence of the Xyld7 polynucleotide of
Populus
(SEQ ID NO 3). SEQ ID NO 3 is located within the QTL region shown in Figure 1.
Figure 9B: shows the nucleotide sequence of the Xyld7 allele A polynucleotide
of
Salix (SEQ ID NO 2).
Figure 9C: shows the nucleotide sequence of the Xyld7 allele C polynucleotide
of
Salix (SEQ ID NO 1).
Figure 9D: shows the nucleotide sequence of the Xyld7 allele A polynucleotide
of
Salix (SEQ ID NO 2) aligned with the Xyld7 allele C polynucleotide of Salix
(SEQ ID
NO 1) to indicate Gene Xyld7 allele A insertion region.
Figure 9E: shows the amino acid sequence of the Xyld7 allele C polypeptide in
Sal ix
(SEQ ID NO 26).
Figure 10A: shows the nucleotide sequence of the Xyld8 polynucleotide of
Populus
(SEQ ID NO 17). SEQ ID NO 17 is located within the QTL region shown in Figure
1.
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Figure 10B: shows the nucleotide sequence of the Xyld8 allele A polynucleotide
of
Salix (SEQ ID NO 18).
Figure 10C: shows the nucleotide sequence of the Xyld8 allele C polynucleotide
of
Salix (SEQ ID NO 19).
Figure IOD: shows the amino acid sequence of the Xyld8 allele A polypeptide of
Salix (SEQ ID NO 34).
Figure IOE: shows the amino acid sequence of the Xyld8 allele C polypeptide of
Salix
(SEQ ID NO 35).
Figure 11A: shows the nucleotide sequence of the Xyld9 polynucleotide of
Populus
(SEQ ID NO 20). SEQ ID NO 20 is located within the QTL region shown in Figure
1.
Figure 11B: shows the nucleotide sequence of the Xyld9 allele A polynucleotide
of
Salix (SEQ ID NO 21).
Figure 1IC: shows the nucleotide sequence of the Xyld9 allele C polynucleotide
of
Salix (SEQ ID NO 22).
Figure 11D: shows the amino acid sequence of the Xyld9 allele A polypeptide of
Salix (SEQ ID NO 36).
Figure I IE: shows the amino acid sequence of the Xyld9 allele C polypeptide
of Salix
(SEQ ID NO 37).
Figure 12A: shows the nucleotide sequence of the Xyld10 polynucleotide of
Populus
(SEQ ID NO 23). SEQ ID NO 23 is located within the QTL region shown in Figure
1.
Figure 12B: shows the nucleotide sequence of the XyldlO allele A
polynucleotide of
Salix (SEQ ID NO 24).
Figure 12C: shows the nucleotide sequence of the XyldlO allele C
polynucleotide of
Salix (SEQ ID NO 25).
Figure 12D: shows the amino acid sequence of the XyldlO allele A polypeptide
of
Salix (SEQ ID NO 38).
Figure 12E: shows the amino acid sequence of the XyldlO allele C polypeptide
of
Salix (SEQ ID NO 39).
Figure 13: shows QTL analysis of yield related traits in the K8 mapping
population
for a 5.1 cM region of chromosome X as delimited by markers X15341094 and
X15945623. QTL confidence intervals are indicated by thick bars (1 LOD below
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peak) and lines (2 LOD below peak). The percentage of the variance explained
by the
QTL is shown in parentheses.
Figure 14 shows representation of the public annotation of the poplar genomic
5 sequence represented by the QTL region. Ten genes are predicted (not to
scale).
Figure 15 shows the QTL region of Figure 1 wherein markers derived from the
sequence that we used in QTL identification are indicated by bold type. Gene
sequences are labelled and underlined.
Figure 16 shows the QTL region of Figure 2 wherein markers derived from the
sequence that we used in QTL identification are indicated by bold type. Gene
sequences are labelled and underlined.
Figure 17 shows the QTL region of Figure 2 wherein the sequence of Xyld7
allele A
has been replaced with Xyld7 allele C.
Figure 18 shows the sequence of a QTL region in Populus associated with
improved
yield wherein the poplar sequence is derived from the public sequence
annotation of
the poplar genome (www.phytozome.net.).
Detailed description
The present invention relates to Xyldl, Xyld2, Xyld3, Xyld4, Xyld5, Xyld6,
Xyld7,
Xyld8, Xyld9 and Xyld10 polynucleotides and polypeptides and homologues
thereof.
In preferred embodiments of the present invention, the polynucleotide
comprises a
nucleotide sequence which encodes a Salix allele C polypeptide selected from
the
group consisting of Xyldl, Xyld2, Xyld3, Xyld4, Xyld5, Xyld6, Xyld7,
Xy1d8,'Xyld9
and Xyld10, or a homologue of said polynucleotide.
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16
In preferred embodiments of the present invention, the polypeptide is a Salix
allele C
polypeptide selected from the group consisting of Xyldl, Xyld2, Xyld3, Xyld4,
Xyld5, Xyld6, Xyld7, Xyld8, Xyld9 and Xyld10, or a homologue of said
polypeptide.
The Xyldl polynucleotide is shown in SEQ ID NO 4 and SEQ ID NO 5. SEQ ID NO
4 (as shown in Figure 3A) shows a sequence of the gene in Populus and SEQ ID
NO
5 (as shown in Figure 3B) shows a sequence of the gene (allele A) in Sal ix.
SEQ ID
NO 27 (as shown in Figure 3C) shows the Salix Xyldl allele A polypeptide
sequence.
The Xyld2 polynucleotide is shown in SEQ ID NO 6 and SEQ ID NO 7. SEQ ID NO
6 (as shown in Figure 4A) shows a sequence of the gene in Populus and SEQ ID
NO
7 (as shown in Figure 4B) shows a sequence of the gene (allele A) in Salix.
SEQ ID
NO 28 (as shown in Figure 4C) shows the Salix Xyld2 allele A in Salix
polypeptide
sequence.
The Xyld3 polynucleotide is shown in SEQ ID NO 8 and SEQ ID NO 9 and
homologues thereof. SEQ ID NO 8 (as shown in Figure 5A) shows a sequence of
the
gene in Populus and SEQ ID NO 9 (as shown in Figure 5B) shows a sequence of
the
gene (allele A) in Salix. SEQ ID NO 29 (as shown in Figure 5C) shows the Salix
Xyld3 allele A polypeptide sequence.
The Xyld4 polynucleotide is shown in SEQ ID NO 10, SEQ ID NO 11 and SEQ ID
NO 12. SEQ ID NO 10 (as shown in Figure 6A) shows a sequence of the gene in
Populus. SEQ ID NO 11 (as shown in Figure 6B) shows a sequence of the gene
(allele A) in Salix. SEQ ID NO 12 (as shown in Figure 6C) shows a sequence of
the
gene (allele C) in Salix. SEQ ID NO 30 (as shown in Figure 6D) shows the Salix
Xyld4 allele A polypeptide sequence. SEQ ID NO 31 (as shown in Figure 6E)
shows
the Sal ix Xyld4 allele C polypeptide sequence.
The Xyld5 polynucleotide is shown in SEQ ID NO 13. SEQ ID NO 13 (as shown in
Figure 7) shows a sequence of the gene in Populus.
The Xyld6 polynucleotide is shown in SEQ ID NO 14, SEQ ID NO 15 and SEQ ID
NO 16. SEQ ID NO 14 (as shown in Figure 8A) shows a sequence of the gene in
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Populus. SEQ ID NO 15 (as shown in Figure 8B) shows a sequence of the gene
(allele
A) in Salix. SEQ ID NO 16 (as shown in Figure 8C) shows a sequence of the gene
(allele C) in Sal ix. SEQ ID NO 32 (as shown in Figure 8D) shows the Salix
Xyld6
allele A polypeptide sequence. SEQ ID NO 33 (as shown in Figure 8E) shows the
Salix Xyld6 allele C polypeptide sequence.
The Xyld7 polynucleotide is shown in SEQ ID NO 3, SEQ ID NO 2 and SEQ ID NO
1. SEQ ID NO 3 (as shown in Figure 9A) shows a sequence of the gene in
Populus.
SEQ ID NO 2 (as shown in Figure 9B) shows a sequence of the gene (allele A) in
Salix. SEQ ID NO 1 (as shown in Figure 9C) -shows a sequence of the gene
(allele C)
in Sal ix. An alignment of Xyld7 allele A (SEQ ID NO 2) sequence with the
Xyld7
allele C sequence (SEQ ID NO 1) (as shown in the alignment of Figure 9D)
indicates
Xyld7 allele A has an insertion region with extra nucleotides that are not
present in
Xyld7 allele C sequence SEQ ID NO 1. SEQ ID NO 26 (as shown in Figure 9E)
shows the Salix Xyld7 allele C polypeptide sequence.
The Xyld8 polynucleotide is shown in SEQ ID NO 17, SEQ ID NO 18 and SEQ ID
NO 19. SEQ ID NO 17 (as shown in Figure 10A) shows a sequence of the gene in
Populus. SEQ ID NO 18 (as shown in Figure 10B) shows a sequence of the gene
(allele A) in Salix. SEQ ID NO 19 (as shown in Figure I OC) shows a sequence
of the
gene (allele C) in Salix. SEQ ID NO 34 (as shown in Figure 1OD) shows the
Salix
Xyld8 allele A polypeptide sequence. SEQ ID NO 35 (as shown in Figure 10E)
shows the Salix Xyld8 allele C polypeptide sequence.
The Xyld9 polynucleotide is shown in SEQ ID NO 20, SEQ ID NO 21 and SEQ ID
NO 22. SEQ ID NO 20 (as shown in Figure 11A) shows a sequence of the gene in
Populus. SEQ ID NO 21 (as shown in Figure 11B) shows a sequence of the gene
(allele A) in Salix. SEQ ID NO 22 (as shown in Figure 1IC) shows a sequence of
the
gene (allele C) in Salix. SEQ ID NO 36 (as shown in Figure 11D) shows the
Salix
Xyld9 allele A polypeptide sequence. SEQ ID NO 37 (as shown in Figure 11E)
shows the Salix Xyld9 allele C polypeptide sequence.
The XyldlO polynucleotide is shown in SEQ ID NO 23, SEQ ID NO 24 and SEQ ID
NO 25. SEQ ID NO 23 (as shown in Figure 12A) shows a sequence of the gene in
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Populus. SEQ ID NO 24 (as shown in Figure 12B) shows a sequence of the gene
(allele A) in Salix. SEQ ID NO 25 (as shown in Figure 12C) shows a sequence of
the
gene (allele C) in Salix. SEQ ID NO 38 (as shown in Figure 12D) shows the
Salix
Xyldl0 allele A polypeptide sequence. SEQ. ID NO 39 (as shown in Figure 12E)
shows the Salix XyldlO allele C polypeptide sequence.
The importance of Xyldl, Xyld2, Xyld3, Xyld4, XyldS, Xyld6, Xyld7, Xyld8,
Xyld9
and XyldlO in genetic improvement in crop plants was established following the
identification of a QTL region in Salix associated with improved harvestable
biomass
yield. The corresponding QTL region in Populus is shown in Figure 1. A
comparison
of this QTL region with information from the Populus trichocarpa genome
database
(http://genome.jgi-psf.org/Poptrl_I/Poptrl-l.home.html) indicated that the QTL
region comprises Xyldl, Xyld2, Xyld3, Xyld4, Xyld5, Xyld6, Xyld7, Xyld8, Xyld9
and Xyld10.
The information provided on Xyldl, Xyld2, Xyld3, Xyld4, Xyld5, Xyld6, Xyld7,
Xyld8, Xyld9 and Xyldl0 provides a route to exploitation in crops, other
cultivated
plants or model plants, not directly related to Populus or Salix as the
information
disclosed herein enables homologous genes to Xyldl, Xyld2, Xyld3, Xyld4,
XyldS,
Xyld6, Xyld7, Xyld8, Xyld9 and Xyld 10 to be identified.
Details of Xyldl, Xyld2, Xyld3, Xyld4, XyldS, Xyld6, Xyld7, Xyld8, Xyld9 and
Xyld 10 are detailed. below:
1. Xyldl
Xyldl shows best homology in Arabidopsis thaliana with Locus AT3G12740, or
ALIS1 (ALA-Interacting Subunit). ALIS1 is a member of a family of phospholipid
transporters (ALIS1 -ALIS5) which are homologs of the Cdc50p/Lem3p family in
yeast that are essential for the trafficking of yeast P4-ATPases. The
Arabidopsis ALIS
proteins are 27-30% identical to yeast Cdc50p and similarity ranges from 48-
53%. In
yeast ALIS 1 shows strong affinity to ALA3. In Arabidopsis, ALAS has been
shown
to be important for trans-Golgi proliferation of slime vesicles containing
polysaccharides and enzymes for secretion. In yeast, ALAS function requires
interaction with the ALIS1. In Arabidopsis plants, ALIS1, like ALA3, is
localised to
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membranes of Golgi-like structures and is expressed in root peripheral
columella
cells. It has been proposed that the ALIS 1 protein is a P- sub-unit of ALA3
in
Arabidopsis and that this protein is important part of the Golgi machinery in
plants
required for secretory processes during development.
Relevant publications
Poulsen LR, Lopez-Marques RL, McDowell SC, Okkeri J, Licht D, Schulz A,
Pomorski T, Harper JF, Palmgren MG. 2008 The Arabidopsis P4-ATPase ALA3
localizes to the golgi and requires a beta-subunit to function in lipid
translocation and
secretory vesicle formation. Plant Cell. 3:658-76.
Bosco CD, Lezhneva L, Biehl A, Leister D, Strotmann H, Wanner G, Meurer J.
2004
Inactivation of the chloroplast ATP synthase gamma subunit results in high non-
photochemical fluorescence quenching and altered nuclear gene expression in
Arabidopsis thaliana. J Biol Chem.279(2):1060-9.
2. Xyld2
Xyld 2 shows strongest homology to Arabidopsis thaliana gene ALDH5FI (Locus
AT1G79440 ; previous nomenclature SSADH; EC 1.2.1.24) which is a member of the
aldehyde dehydrogenases (ALDHs) protein superfamily of NAD(P)C-dependent
enzymes that oxidize a wide range of endogenous and exogenous aliphatic and
aromatic aldehydes. The Arabidopsis genome contains 14 unique ALDH sequences
encoding members of nine ALDH families, including eight known families and one
novel family (ALDH22) that is currently known only in plants. Of these,
there is one succinic semialdehyde dehydrogenase gene, ALDH5FJ, which encodes
a
protein of 528 amino acids. ALDH5F1 is the only confirmed identified member of
the
succinic semialdehyde family in plants. The Arabidopsis protein is localized
to
mitochondria and a kinetic analysis showed that the recombinant enzyme was
specific
for succinic semialdehyde and regulated by adenine nucleotides. T-DNA knockout
mutants of ALDH5FJ result in dwarfed plants with necrotic lesions and are
sensitive
to both ultraviolet-B light and heat stress. Plants with ssadh mutations
accumulate
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elevated levels of H202, suggesting a role for this gene in stress regulation
detoxification pathway plant, providing defense against environmental stress
by
preventing the accumulation of reactive oxygen species.
5 Relevant publications
Hueser, AF, UI L. 2008 Analysis of GABA-shunt metabolites in Arabidopsis
thaliana
19th International Conference on Arabidopsis Research
10 Ludewig F, Hi ser A, Fromm H, Beauclair L, Bouche N. 2008 Mutants of GABA
transaminase (POP2) suppress the severe phenotype of succinic semialdehyde
dehydrogenase (ssadh) mutants in Arabidopsis. PLoS ONE 3(10):e3383
Zybailov B, Rutschow H, Friso G, Rudella A, Emanuelsson 0, Sun Q, van Wijk KJ.
15 2008 Sorting signals, N-terminal modifications and abundance of the
chloroplast
proteome. PLoS ONE 3(4):e1994
Fait A, Yellin A, Fromm H. 2005 GABA shunt deficiencies and accumulation of
reactive oxygen intermediates: insight from Arabidopsis mutants. FEBS Lett.
20 579(2):415-20
Kirch HH, Bartels D, Wei Y, Schnable PS, Wood AJ. 2004 The ALDH gene
superfamily of Arabidopsis. Trends Plant Sci. 9(8):371-7
Breitkreuz KE, Allan WL, Van Cauwenberghe OR, Jakobs C, Talibi D, Andre B,
Shelp BJ. 2003 A novel gamma-hydroxybutyrate dehydrogenase: identification and
expression of an Arabidopsis cDNA and potential role under oxygen deficiency.
J
Biol Chem. 278(42):41552-6
3. Xyld3
Xyld3 shows strongest homology with Arabidopsis thaliana ALTERED PHLOEM
DEVELOPMENT (APL) gene (Locus AT1G79430), which encodes a MYB coiled-
coil-type transcription factor that is required for phloem identity in
Arabidopsis. APL
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has been proposed to have a dual role both in promoting phloem differentiation
and in
repressing xylem differentiation during vascular development.
Relevant publications
Truemit E, Bauby H, Dubreucq B, Grandjean 0, Runions J, Barthelemy J, Palauqui
JC. 2008 High-resolution whole-mount imaging of three-dimensional tissue
organization and gene expression enables the study of Phloem development and
structure in Arabidopsis. Plant Cell. 20(6):1494-503
Lehesranta S, Lindgren 0, Taehtiharju S, Carlsbecker A, Helariutta Y 2008 The
role
of APL as a transcriptional regulator in specifying vascular identity 19th
International
Conference on Arabidopsis Research
Carlsbecker A, Lindgren 0, Bonke M, Thitamadee S, Tahtiharju S, Helariutta Y
2004
Genetic analysis of procambial development in the Arabidopsis root 15th
International Conference on Arabidopsis Research
Bonke M, Hauser M-T, Helariutta Y 2002 The APL locus is required for phloem
development in Arabidopsis roots. 13th International Conference on Arabidopsis
Research
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4. Xyld4
Xyld4 show strongest homology in Arabidopsis thaliana to Locus AT1G79420.
Function not yet described.
5. Xy1d5
XyldS shows strongest homology with AtOCT2 in Arabidopsis thaliana (Locus
AT1G79360). ATOCT2 is one of six Arabidopsis organic cation/carnitine
transporter
(OCT) -like proteins, named AtOCTI-AtOCT6 (loci Atlg73220, Atlg79360,
Atlg16390, At3g20660, Atlg79410 and At1g16370, respectively) that have been
identified. These proteins cluster in a small subfamily within the `organic
solute
cotransporters' included in the large sugar transporter family of the major
facilitator
superfamily (MFS). AtOCTI shares features of organic cation/camitine
transporters
(OCTs). In animals, mammalian plasma membrane OCTs are involved in homeostasis
and distribution of various small endogenous amines (e.g. carnitine, choline)
and
detoxification of xenobiotics such as nicotine. AtOCTI is able to transport
carnitine in
yeast and is likely to be involved in the transport of carnitine or related
molecules
across the plasma membrane in plants.
The orthologous gene sequence has not yet been identified in willow.
Related publication
Tohge T, Nishiyama Y, Hirai MY, Yano M, Nakajima J, Awazuhara M, Inoue E,
Takahashi H, Goodenowe DB, Kitayama M, Noji M, Yamazaki M, Saito K. 2005
Functional genomics by integrated analysis of metabolome and transcriptome of
Arabidopsis plants over-expressing an MYB transcription factor. Plant J.
42(2):218-
30
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23
6. Xy1d6
Xyld6 shows best fit with ATOCT3 Arabidopsis ORGANIC CATION/CARNITINE
TRANSPORTER2). ATOCT3 is one of six Arabidopsis organic cation/carnitine
transporter (OCT) -like proteins, named AtOCTI-AtOCT6 (loci At1g73220,
At1g79360, At1g16390, At3g20660, At1g79410 and At1g16370, respectively)
referred to above. These proteins cluster in a small subfamily within the
`organic
solute cotransporters' included in the large sugar transporter family of the
major
facilitator superfamily (MFS).
Relevant publications
Lelandais-Briere C, Jovanovic M, Torres GA, Perrin Y, Lemoine R, Corre-Menguy
F,
Hartmann C. 2007 Disruption of AtOCTI, an organic cation transporter gene,
affects
root development and carnitine-related responses in Arabidopsis. Plant J.
51(2):154-
64
Price J, Laxmi A, St Martin SK, Jang JC. 2004 Global transcription profiling
reveals
multiple sugar signal transduction mechanisms in Arabidopsis. Plant Cell.
16(8):2128-
50
7. Xyld7
Xyld7 shows homology with members of the R2R3-type MYB gene family in
Arabidopsis. Although no functional data are available for most of the 125
R2R3-type
AtMYB genes, a number of functions have been assigned concerning many aspects
of
plant secondary metabolism, as well as the identity and fate of plant cells.
This
includes regulation of phenylpropanoid metabolism, control of development and
determination of cell fate and identity, plant responses to environmental
factors and
mediating hormone actions.
Relevant publications
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24
Stracke R, Werber M, Weisshaar B. 2001 The R2R3-MYB gene family in
Arabidopsis thaliana. Curr Opin Plant Biol. 4(5):447-56
Riechmann JL, Heard J, Martin G, Reuber L, Jiang C, Keddie J, Adam L, Pineda
0,
Ratcliffe OJ, Samaha RR, Creelman R, Pilgrim M, Broun P, Zhang JZ, Ghandehari
D,
Sherman BK, Yu G. 2000 Arabidopsis transcription factors: genome-wide
comparative analysis among eukaryotes. Science. 290(5499):2105-10
8. Xyld8
Xyld8 shows best fit with ANAC028, Arabidopsis NAC domain containing protein
(Locus AT1G65910). NAC (NAM, ATAF, and CUC) is a plant-specific gene family.
NAC family transcription factors are involved in maintaining organ or tissue
boundaries regulating the transition from growth by cell division to growth by
cell
15. expansion. Most NAC proteins contain a highly conserved N-terminal DNA-
binding
domain, a nuclear localization signal sequence, and a variable C-terminal
domain. 75
and 105 NAC genes were predicted in the Oryza sativa and Arabidopsis genomes,
respectively. The functions of only some of these have been described. The
first
reported NAC genes were NAM from petunia and CUC2 from Arabidopsis that
participate in shoot apical meristem development. CUCI, CUC2 and nam are
expressed at the boundaries between cotyledonary primordial and between floral
organs and are specifically involved in shoot apical meristem formation and
separation of cotyledons and floral organs: Other development-related NAC
genes
have been suggested with roles in controlling cell expansion of specific
flower organs
e.g. NAP or auxindependent formation of the lateral root system e.g. NAC1.
Some of
NAC genes, such as ATAFI and ATAF2 genes from Arabidopsis and the StNAC gene
from potato, are induced by pathogen attack and wounding. More recently, a few
NAC
genes, such as AtNAC072 (RD26), AtNAC019, AtNAC055 from Arabidopsis, and
BnNAC from Brassica (31), were found to be involved in responses to
environmental
stress. Seven members of NAC family At2g18060, At4g36160, At5g66300,
At1g12260, Atlg62700, At5g62380, and At1g71930 have been designated as
VASCULAR-RELATED NAC-DOMAIN PROTEIN 1 (VNDI to VND7). Members of
these could induce transdifferentiation of various cells into metaxylem- and
protoxylem-like vessel elements, respectively, in Arabidopsis and poplar.
Similarly
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ANAC012 and ANAC073 also appear to have a role in xylem development and
secondary wall thickening in Arabidopis.
Relevant publications
5
Ooka H, Satoh K, Doi K, Nagata T, Otomo Y, Murakami K, Matsubara K, Osato N,
Kawai J, Caminci P, Hayashizaki Y, Suzuki K, Kojima K, Takahara Y, Yamamoto K,
Kikuchi S. 2003 Comprehensive analysis of NAC family genes in Oryza sativa and
Arabidopsis thaliana. DNA Res. 10(6):239-47
Riechmann JL, Heard J, Martin G, Reuber L, Jiang C, Keddie J, Adam L, Pineda
0,
Ratcliffe OJ, Samaha RR, Creelman R, Pilgrim M, Broun P, Zhang JZ, Ghandehari
D,
Sherman BK, Yu G. 2000 Arabidopsis transcription factors: genome-wide
comparative analysis among eukaryotes. Science 290(5499):2105-10
9. Xyld9
Xyld9 show strongest homology in Arabidopsis thaliana to Locus AT1G79390. The
function of this expressed protein has not yet been described
10. Xyld10
XyldlO shows homology to the RGLG2 (RING DOMAIN LIGASE2) locus of
Arabidopsis thaliana (Locus AT1G79380). In functional terms, the RING domain
can
basically be considered a protein-interaction domain. RING-finger proteins
have been
implicated in a range of diverse biological processes and biochemical
activities, from
transcriptional and translational regulation to targeted protein degradation.
Relevant publications
Kosarev P, Mayer KF, Hardtke CS. 2002 Evaluation and classification of RING-
fmger domains encoded by the Arabidopsis genome. Genome Biol. 3(4):RESEARCH
0016.1
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26
Further homologous genes to Xyldl, Gene Xyld2, Gene Xyld3, Gene Xyld4, Gene
Xyld6, Gene Xyld7, Gene Xyld8, Gene Xyld9 and Gene XyldlO can be identified,
for
example, through in silico sequence similarity searches for crops/cultivated
or model
plants for which such sequence resources exist. Where such resources are
lacking,
standard molecular biology methods can be employed to clone homologous genes.
As
examples, degenerate primers can designed to amino acid sequences and used in
PCR
to amplify and clone target genes, or alternatively, sequences can be used in
hybridisation approaches if sufficient similarity is expected.
Once homologous genes are identified by any such approach, and the crop/plant
specific sequence is determined, polymorphisms within a given gene can
identified
through sequencing or restriction analysis, as examples.
1. Direct application in genetic improvement.
The gene defined here facilitates direct use for selection of high yielding
plants in
crop breeding programmes. Several laboratories have collections of polymorphic
markers for general use in mapping studies or for assessing genetic diversity.
Now
that the gene has been identified here and a sequence provided, if markers
linked to
the gene described here are available in these laboratories they could be
directly
employed in selection programmes for improving yield.
The efficiency of the use of QTL-associated marker in marker-assisted
selection
strategies will be dependent on the degree of genetic linkage that exists
between the
marker to be used and the causal polymorphism that underlies the QTL. To
maximise
the efficiency of marker-assisted selections based on a QTL, such as that
described
here, markers that are tightly linked to the region would be required to
minimise the
likelihood that linkage between the marker and the causal polymorphism will
breakdown through recombination. The information described here provides a
route
to efficient achievement of the identification of markers whose linkage to the
causal
polymorphism will not be broken easily by recombination. Although anonymous
markers such as Amplified Fragment Length Polymorphism (AFLP) and Random
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27
Amplified Polymorphism (RAPD) classes for example, could be screened in large
numbers to identify those that may fall into regions of the genome linked to
the QTL
by chance, more efficient methods based on the sequence information provided
here
can be used in more direct approaches.
Using knowledge of the underlying sequence information that is publicly
available in
Populus (http://genome jgi-psf org/Poptrl_I/Poptrl_l.home.html) or that which
is
provided here for willow, specific markers can be developed that are targeted
directly
at this region or to a region that is closely linked in genetic terms. Markers
of this
class could include, as examples, microsatellite markers, Restriction Length
Fragment
Length Polymoprhisms (RFLP), Cleaved Amplified Polymorphisms (CAPS), Single
Nucleotide Polymorphisms (SNPS) and INSertion/DELetion (INDEL5). For
microsatellite markers, primer pairs that amplify potentially highly
polymorphic
simple sequence repeat units could be designed from Salix or Populus sequence
in this
region. These could be specific to either genus or could be directly
transferable from
one genus to the other, if nucleotide sequence is sufficiently conserved at
the priming
sites. This is often true if priming sites are selected within coding regions
(Hanley,
S.J., Mallott, M.D. & Karp A. (2006) Tree Genetics and Genomes, 3, 35-48)
(Hanley
et al, 2006). Microsatellite primer sets would then be tested for their
ability to detect
polymoprhisms in the germplasm under study, and those that distinguish between
alleles could be used in marker-assisted selections. Similarly, for the
development of
other markers types (SNP, CAPS, INDEL) sequence information for the QTL region
could be used to design primer sets to generate amplicons that could then be
examined
for polymorphisms in the germplasm under study, either from sequencing or
restriction digestion analysis.
2. Application in transgenic genetic improvement strategies.
The sequences supplied provide a route to crop improvement through genetic
manipulation via transgenic approaches. The sequences provided could be used
directly to generate constructs for testing in transformation experiments.
Such
experiments may involve overexpression, gene-silencing or introduction of a
beneficial allele into any recipient genotype. Such experiments may utilise
the Salix
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or Populus sequences provided here or be based on homologous genes derived
from
any plant of interest.
This disclosure relates to representative markers, and alleles thereof, that
correspond
to and identify a locus that is associated with harvestable yield.
The methods, markers, and alleles of the present invention provide a simple,
inexpensive and reliable means of identifying the haplotype associated with
the
harvestable biomass yield locus. By identifying the chromosome haplotype in
this
region, it is possible to predict whether the harvestable biomass yield
associated QTL
contributes to small or large yield of plant.
Thus, one aspect of this disclosure concerns markers (and alleles thereof)
genetically
linked to a polynucleotide sequence having at least 50, 55, 60, 65, 70, 75,
80, 85, 90,
95, 97, 98, 99 or 100% identity to SEQ ID NO 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
11, 12, 13,
14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25, which is associated with a
harvestable
biomass yield associated QTL that provides a contribution to harvestable
biomass
yield in willow.
Another aspect of this disclosure concerns markers (and alleles thereof)
genetically
linked to a polynucleotide sequence having at least 50, 55, 60, 65, 70, 75,
80, 85, 90,
95, 97, 98, 99 or 100% identity to a nucleotide sequence encoding the
polypeptide of
SEQ ID NO 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38 or 39, which is
associated with a harvestable biomass yield associated QTL that provides a
contribution to harvestable biomass yield in willow.
Kits including probes that detect the markers described herein are also a
feature of this
disclosure.
Another aspect of this disclosure concerns a method for predicting harvestable
biomass yield in a crop plant. The method can include genotyping a sample
obtained
from a subject crop plant for one or more markers genetically linked to a
polynucleotide sequence having at least 50, 55, 60, 65, 70, 75, 80, 85, 90,
95, 97, 98,
99 or 100% identity to SEQ ID NO 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
14, 15, 16,
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17, 18, 19, 20, 21, 22, 23, 24 or 25. The markers are chosen to individually
or
collectively identify a haplotype associated with harvestable biomass yield.
The
haplotype is correlated with harvestable biomass yield providing a prediction
of the
harvestable biomass yield of the subject plant.
A further aspect of this disclosure concerns a method for predicting
harvestable
biomass yield in a crop plant. The method can include genotyping a sample
obtained
from a subject crop plant for one or more markers genetically linked to a
polynucleotide sequence having at least 50, 55, 60, 65, 70, 75, 80, 85, 90,
95, 97, 98,
99 or 100% identity to a nucleotide sequence encoding the polypeptide of SEQ
ID NO
26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38 or 39. The markers are
chosen to
individually or collectively identify a haplotype associated with harvestable
biomass
yield. The haplotype is correlated with harvestable biomass yield providing a
prediction of the harvestable biomass yield of the subject plant.
In certain embodiments, the haplotype is correlated with harvestable biomass
yield by
comparing the haplotype to an index of average harvestable biomass yield by
plant
variety.
Definitions
The poplar and willow chromosomes are referred to as 'linkage groups'. This is
because there are more sequence contigs than chromosomes in the poplar
assembly.
An "allele" is understood within the scope of the invention to refer to a
given form of
a gene, or of any kind of identifiable genetic element such as a marker, that
occupies a
specific position or locus on a chromosome. Variant forms of genes occurring
at the
same locus are said to be alleles of one another. In a diploid cell or
organism, the two
alleles of a given gene (or marker) typically occupy corresponding loci on a
pair of
homologous chromosomes.
An allele associated with a quantitative trait may comprise a single gene or
multiple
genes or even a gene encoding a genetic factor contributing to the phenotype
represented by said QTL.
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The term "breeding", and grammatical variants thereof, refer to any process
that
generates a progeny individual. Breedings can be sexual or asexual, or any
combination thereof. Exemplary non-limiting types of breedings include
crossings,
5 selfings, doubled haploid derivative generation, and combinations thereof.
By "exogenous gene/polynucleotide" it is meant that the gene/polynucleotide is
transformed into the unmodified plant from an external source. The exogenous
nucleotide may, for example, be derived from a genomic DNA or cDNA sequence.
10 Typically the exogenous gene is derived from a different source and has a
sequence
different to the endogenous gene. Alternatively, introduction of an exogenous
gene
having a sequence identical to the endogenous gene may be used to increase the
number of copies of the endogenous gene sequence present in the plant.
15 The term "Homozygous" refers to like alleles at one or more corresponding
loci on
homologous chromosomes.
The term "Heterozygous refers to unlike alleles at one or more corresponding
loci on
homologous chromosomes.
The term "Gene" refers to a unit of DNA which performs one function. Usually,
this
is equated with the production of one RNA or one protein. A gene may contain
coding
regions, introns, untranslated regions and control regions.
As used herein, the phrase "genetic marker" refers to a feature of an
individual's
genome (e.g., a nucleotide or a polynucleotide sequence that is present in an
individual's genome) that is associated with one or more loci of interest.
Typically, a
genetic marker is polymorphic and the variant forms (or llel. Genetic markers
include,
for example, single nucleotide polymorphisms (SNPs), indels (i.e.,
insertions/deletions), simple sequence repeats (SSRs), restriction fragment
length
polymorphisms (RFLPs), random amplified polymorphic DNAs (RAPDs), cleaved
amplified polymorphic sequence (CAPS) markers, Diversity Arrays Technology
(DArT) markers, and amplified fragment length polymorphisms (AFLPs),
Microsatellites or Simple sequence repeat (SSRs) among many other examples.
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Genetic markers can, for example, be used to locate genetic loci containing
alleles that
contribute to variability in expression of phenotypic traits on a chromosome.
A genetic marker can be physically located in a position on a chromosome that
is
within or outside of to the genetic locus with which it is associated (i.e.,
is intragenic
or extragenic, respectively). Stated another way, whereas genetic markers are
typically employed when the location on a chromosome of the gene that
corresponds
to the locus of interest has not been identified and there is a non-zero rate
of
recombination between the genetic marker and the locus of interest, the
presently
disclosed subject matter can also employ genetic markers that are physically
within
the boundaries of a genetic locus (e.g., inside a genomic sequence that
corresponds to
a gene such as, but not limited to a polymorphism within an intron or an exon
of a
gene). In some embodiments of the presently disclosed subject matter, the one
or
more genetic markers comprise between one and ten markers, and in some
embodiments the one or more genetic markers comprise more than ten genetic
markers.
The term "genotype" refers to the set of alleles present in a subject at one
or more loci
under investigation. At any one autosomal locus a geneotype will be either
homozygous (with two identical alleles) or heterozygous (with two different
alleles).
The term "haplotype" refers to the set of alleles an individual inherited from
one
parent. A diploid individual thus has two haplotypes. The term "haplotype" can
be
used in a more limited sense to refer to physically linked and/or unlinked
genetic
markers (e.g., sequence polymorphisms) associated with a phenotypic trait. The
phrase "haplotype block" (sometimes also referred to in the literature simply
as a
haplotype) refers to a group of two or more genetic markers that are
physically linked
on a single chromosome (or a portion thereof). Typically, each block has a few
common haplotypes, and a subset of the genetic markers (i.e., a "haplotype
tag") can
be chosen that uniquely identifies each of these haplotypes.
As used herein, the terms "hybrid", "hybrid plant," and "hybrid progeny"
refers to an
individual produced from genetically different parents (e.g., a genetically
heterozygous or mostly heterozygous individual).
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If two individuals possess the same allele at a particular locus, the alleles
are termed
"identical by descent" if the alleles were inherited from one common ancestor
(i.e.,
the alleles are copies of the same parental allele). The alternative is that
the alleles are
"identical by state" (i.e., the alleles appear the same but are derived from
two different
copies of the allele). Identity by descent information is useful for linkage
studies; both
identity by descent and identity by state information can be used in
association studies
such as those described herein, although identity by descent information can
be
particularly useful.
The term "linkage"/ "genetic linkage", and grammatical variants thereof,
refers to the
association of two or more (and/or traits) at positions on the same
chromosome,
preferably such that recombination between the two loci is reduced to a
proportion
significantly less than 50%. The term linkage can also be used in reference to
the
association between one or more loci and a trait if an allele (or alleles) and
the trait, or
absence thereof, are observed together in significantly greater than 50% of
occurrences. A linkage group is a set of loci, in which all members are linked
either
directly or indirectly to all other members of the set.
"linkage disequilibrium" (also called "allelic association") refers to a
phenomenon
wherein particular alleles at two or more loci tend to remain together in
linkage
groups when segregating from parents to offspring with a greater frequency
than
expected from their individual frequencies in a given population. For example,
a
genetic marker allele and a QTL allele can show linkage disequilibrium when
they
occur together with frequencies greater than those predicted from the
individual allele
frequencies. Linkage disequilibrium can occur for several reasons including,
but not
limited to the alleles being in close proximity on a chromosome
"Locus" refers to a region on a chromosome, which comprises a gene or a
genetic
marker or the like.
As used herein, the phrase "nucleic acid" refers to any physical string of
monomer
units that can be corresponded to a string of nucleotides, including a polymer
of
nucleotides (e.g., a typical DNA, cDNA or RNA polymer), modified
oligonucleotides
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(e.g., oligonucleotides comprising bases that are not typical to biological
RNA or
DNA, such as T-0-methylated oligonucleotides), and the like. In some
embodiments,
a nucleic acid can be single-stranded, double-stranded, multi-stranded, or
combinations thereof. Unless otherwise indicated, a particular nucleic acid
sequence
of the presently disclosed subject matter optionally comprises or encodes
complementary sequences, in addition to any sequence explicitly indicated.
The term "protein" includes single-chain polypeptide molecules as well as
multiple-
polypeptide complexes where individual constituent polypeptides are linked by
covalent or non-covalent means.
The phrase "phenotypic trait" refers to the appearance or other detectable
characteristic of an individual, resulting from the interaction of its genome
with the
environment.
"The term Microsatellite or SSRs (Simple sequence repeats) (Marker)" refers to
a type
of genetic marker that consists of numerous repeats of short sequences of DNA
bases,
which are found at loci throughout the plant's DNA and have a likelihood of
being
highly polymorphic.
"Polymorphism" refers to the presence in a population of two or more different
forms
of a gene, genetic marker, or inherited trait.
The term "quantitative trait locus" (QTL) refers to an association between a
genetic
marker and a chromosomal region and/or gene that affects the phenotype of a
trait of
interest. Typically, this is determined statistically; e.g., based on one or
more methods
published in the literature. A QTL can be a chromosomal region and/or a
genetic
locus with at least two alleles that differentially affect the expression of a
phenotypic
trait (either a quantitative trait or a qualitative trait).
"Sequence Homology or Sequence identity" is used herein interchangeably. The
terms
"identical" or percent "identity" in the context of two or more nucleic acid
or protein
sequences, refer to two or more sequences or subsequences that are the same or
have a
specified percentage of amino acid residues or nucleotides that are the same,
when
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compared and aligned for maximum correspondence, as measured using one of the
following sequence comparison algorithms or by visual inspection. If two
sequences
which are to be compared with each other differ in length, sequence identity
preferably relates to the percentage of the nucleotide residues of the shorter
sequence
which are identical with the nucleotide residues of the longer sequence.
Sequence
identity can be determined conventionally with the use of computer programs
such as
the Bestfit program (Wisconsin Sequence Analysis Package, Version 8 for Unix,
Genetics Computer Group, University Research Park, 575 Science Drive Madison,
Wl
53711). Bestfit utilizes the local homology algorithm of Smith and Waterman,
Advances in Applied Mathematics 2 (1981), 482-489, in order to find the
segment
having the highest sequence identity between two sequences. When using Bestfit
or
another sequence alignment program to determine whether a particular sequence
has
for instance 95% identity with a reference sequence of the present invention,
the
parameters are preferably so adjusted that the percentage of identity is
calculated over
the entire length of the reference sequence and that homology gaps of up to 5%
of the
total number of the nucleotides in the reference sequence are permitted. When
using
Bestfit, the so-called optional parameters are preferably left at their preset
("default")
values. The deviations appearing in the comparison between a given sequence
and the
above-described sequences of the invention may be caused for instance by
addition,
deletion, substitution, insertion or recombination. Such a sequence comparison
can
preferably also be carried out with the program "fasta20u66" (version 2.0u66,
September 1998 by William R. Pearson and the University of Virginia; see also
W.R.
Pearson (1990), Methods in Enzymology 183, 63-98, appended examples and
http://workbench.sdsc.edu/). For this purpose, the "default" parameter
settings may be
used.
Preferably, reference to a sequence which has a percent identity to any one of
SEQ ID
NOs: 1-43 as detailed herein refers to a sequence which has the stated percent
identity
over the entire length of the SEQ ID NO referred to.
Another indication that two nucleic acid sequences are substantially identical
is that
the two molecules hybridize to each other under stringent conditions.
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In general, unless otherwise specified, when referring to a "plant" it is
intended to
cover a plant at any stage of development, including sing cells and seeds.
Thus, in
particular embodiments, the present invention provides a plant cell.
5 A "plant cell" is a structural and physiological unit of a plant, comprising
a protoplast
and a cell wall. The plant cell may be in form of an isolated single cell or a
cultured
cell, or as a part of higher organized unit such as, for example, plant
tissue, a plant
organ, or a whole plant.
10 "Plant cell culture" means cultures of plant units such as, for example,
protoplasts,
cell culture cells, cells in plant tissues, pollen, pollen tubes, ovules,
embryo sacs,
zygotes and embryos at various stages of development.
"Plant material" refers to leaves, stems, roots, flowers or flower parts,
fruits, pollen,
15 egg cells, zygotes, seeds, cuttings, cell or tissue cultures, or any other
part or product
of a plant.
A "plant organ" is a distinct and visibly structured and differentiated part
of a plant
such as a root, stem, leaf, flower bud, or embryo.
"Plant tissue" as used herein means a group of plant cells organized into a
structural
and functional unit. Any tissue of a plant in planta or in culture is
included. This term
includes, but is not limited to, whole plants, plant organs, plant seeds,
tissue culture
and any groups of plant cells organized into structural and/or functional
units. The use
of this term in conjunction with, or in the absence of, any specific type of
plant tissue
as listed above or otherwise embraced by this definition is not intended to be
exclusive of any other type of plant tissue.
"Harvestable biomass yield" is calculated according to the plants parts that
constitute
relevant harvestable product. In one embodiment, a harvestable biomass yield
corresponds to the total of the above ground biomass being the harvestable
product.
Preferred examples, where the harvestable product of the crop may be the above
ground biomass are trees such as, for example (but not limited to), Salex or
Popular.
In another embodiment, a harvestable biomass yield corresponds to only one
part of
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the plant being the harvestable product. Preferred examples, where the
harvestable
product of the crop may be a part of the plant are parts of food crops such
as, for
example (but not limited to), the kernel in maize or the grain in rice.
The genomic DNA can be assayed to determine which markers are present using
any
method known in.the art. For example, single-strand conformation polymorphism
(SSCP) analysis, base excision sequence scanning (BESS), restriction fragment
length
polymorphism (RFLP) analysis, heteroduplex analysis, denaturing gradient gel
electrophoresis (DGGE), temperature gradient electrophoresis, allelic
polymerase
chain reaction (PCR), ligase chain reaction direct sequencing, mini
sequencing,
nucleic acid hybridization, or micro-array-type detection can be used to
identify the
polymorphisms present in the sample.
The methods described herein include genotyping a sample of genetic material
obtained from a subject plant for one or more markers to determine the allele
present
at the marker locus.
Detection of alleles
The nucleic acids obtained from the sample can be genotyped to identify the
particular
allele present for a marker locus. A sample of sufficient quantity to permit
direct
detection of marker alleles from the sample can be obtained from the plant.
Alternatively, a smaller sample is obtained from the subject and the nucleic
acids are
amplified prior to detection. Optionally, the nucleic acid sample is purified
(or
partially purified) prior to detection of the marker alleles. Any target
nucleic that is
informative for a chromosome haplotype in the interval corresponding to the
sequence
located between reference nucleotide position A and reference nucleotide
position B
can be detected. The target nucleic acid may correspond to a marker locus
localized
in this interval. Any method of detecting a nucleic acid molecule can be used,
such as
hybridization and/or sequencing assays.
Hybridization
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Hybridization is the binding of complementary strands of DNA, DNA/RNA, or RNA.
Hybridization can occur when primers or probes bind to target sequences such
as
target sequences within willow genomic DNA. Probes and primers that are useful
generally include nucleic acid sequences that hybridize (for example under
high
stringency conditions) with at least 10, 12, 14, 16, 18, or 20 to the
sequences
provided. Physical methods of detecting hybridization or binding of
complementary
strands of nucleic acid molecules, include but are not limited to, such
methods as
DNase I or chemical footprinting, gel shift and affinity cleavage assays,
Southern and
Northern blotting, dot blotting and light absorption detection procedures. The
binding
between a nucleic acid primer or probe and its 26 target nucleic acid is
frequently
characterized by the temperature (Tm) at which 50% of the nucleic acid probe
is
melted from its target. A higher (Tm) means a stronger or more stable complex
relative to a complex with a lower (Tm).
More generally, complementary nucleic acids form a stable duplex or triplex
when the
strands bind, (hybridize), to each other by forming Watson-Crick, Hoogsteen or
reverse Hoogsteen base pairs. Stable binding occurs when an oligonucleotide
molecule remains detectably bound to a target nucleic acid sequence under the
required conditions.
Complementarity is the degree to which bases in one nucleic acid strand base
pair
with the bases in a second nucleic acid strand. Complementarity is
conveniently
described by percentage, that is, the proportion of nucleotides that form base
pairs
between two strands or within a specific region or domain of two strands.
For example, if 10 nucleotides of a 15-nucleotide oligonucleotide form base
pairs with
a targeted region of a DNA molecule, that oligonucleotide is said to have
66.67%
complementarity to the region of DNA targeted.
`Sufficient complementarity' means that a sufficient number of base pairs
exist
between an oligonucleotide molecule and a target nucleic acid sequence to
achieve
detectable binding. When expressed or measured by percentage of base pairs
formed,
the percentage complementarity that fulfills this goal can range from as
little as about
50% complementarity to full (100%) complementary. In general, sufficient
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complementarity is at least about 50%, for example at least about 75%
complementarity, at least about 90% complementarity, at least about 95%
complementarity, at least about 98% complementarity, or even at least about
100%
complementarity.
A thorough treatment of the qualitative and quantitative considerations
involved in
establishing binding conditions that allow one skilled in the art to design
appropriate
oligonucleotides for use under the desired conditions is provided by Beltz et
al.
Methods Enzymol 100:266-285, 1983, and by Sambrook et al. (ed.), 27 Molecular
Cloning: A Laboratory Manual, 2nd ed., vol. 1-3, Cold Spring Harbor Laboratory
Press, Cold Spring Harbor, NY, 1989.
Hybridization conditions resulting in particular degrees of stringency will
vary
depending upon the nature of the hybridization method and the composition and
length of the hybridizing nucleic acid sequences. Generally, the temperature
of
hybridization and the ionic strength (such as the Na+ concentration) of the
hybridization buffer will determine the stringency of hybridization.
Calculations
regarding hybridization conditions for attaining particular degrees of
stringency are
discussed in Sambrook et al., (1989) Molecular Cloning: a laboratory manual,
second
edition, Cold Spring Harbor Laboratory, Plainview, NY (chapters 9 and I 1).
The following is an exemplary set of hybridization conditions and is not
limiting.
Very High Stringency (detects sequences that share at least 90%
complementarity)
Hybridization: 5x SSC at 65 C for 16 hours
Wash twice: 2x SSC at room temperature (RT) for 15 minutes each
Wash twice: 0.5x SSC at 65 C for 20 minutes each
High Stringency (detects sequences that share at least 80% complementarity)
Hybridization: 5x-6x SSC at 65 C-70 C for 16-20 hours
Wash twice: 2x SSC at RT for 5-20 minutes each
Wash twice: lx SSC at 55 C-70 C for 30 minutes each
Low Stringency (detects sequences that share at least 50% complementarily)
Hybridization: 6x SSC at RT to 55 C for 16-20 hours
Wash at least twice: 2x-3x SSC at RT to 55 C for 20-30 minutes each.
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Methods for labeling nucleic acid molecules so they can be detected are well
known.
Examples of such labels include non-radiolabels and radiolabels. Non-
radiolabels
include, but are not limited to an enzyme, chemiluminescent compound,
fluorescent
compound (such as FITC, Cy3, and Cy5), metal complex, hapten, enzyme,
colorimetric agent, a dye, or combinations thereof. Radiolabels include, but
are not
limited to, 1251 and 35S. For example, radioactive and fluorescent labeling
methods, as
well as other methods known in the art, are suitable for use with the present
disclosure. In one example, primers used to amplify the subject's nucleic
acids are
labeled (such as with biotin, a radiolabel, or a fluorophore). In another
example,
amplified target nucleic acid samples are end-labeled to form labeled 28
amplified
material. For example, amplified nucleic acid molecules can be labeled by
including
labeled nucleotides in the amplification reactions.
Nucleic acid molecules associated corresponding to one or more marker loci can
also
be detected by hybridization procedures using a labeled nucleic acid probe,
such as a
probe that detects only one alternative allele at a marker locus. Most
commonly, the
target nucleic acid (or amplified target nucleic acid) is separated based on
size or
charge and transferred to a solid support. The solid support (such as membrane
made
of nylon or nitrocellulose) is contacted with a labeled nucleic acid probe,
which
hybridizes to it complementary target under suitable hybridization conditions
to form
a hybridization complex.
Hybridization conditions for a given combination of array and target material
can be
optimized routinely in an empirical manner close to the Tm of the expected
duplexes,
thereby maximizing the discriminating power of the method. For example, the
hybridization conditions can be selected to permit discrimination between
matched
and mismatched oligonucleotides. Hybridization conditions can be chosen to
correspond to those known to be suitable in standard procedures for
hybridization to
filters (and optionally for hybridization to arrays). In particular,
temperature is
controlled to substantially eliminate formation of duplexes between sequences
other
than an exactly complementary allele of the selected marker. A variety of
known
hybridization solvents can be employed, the choice being dependent on
considerations
known to one of skill in the art (see U.S. Patent 5,981,185).
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Once the target nucleic acid molecules have been hybridized with the labeled
probes,
the presence of the hybridization complex can be analyzed, for example by
detecting
the complexes.
5 Methods for detecting hybridized nucleic acid complexes are well known in
the art. In
one example, detection includes detecting one or more labels present on the
oligonucleotides, the target (e.g., amplified) sequences, or both. Detection
can include
treating the hybridized complex with a buffer and/or a conjugating solution to
effect
conjugation or coupling of the hybridized complex with the detection label,
and
10 treating the conjugated, hybridized complex with a detection reagent. In
one example,
the conjugating solution includes streptavidin alkaline phosphatase, avidin
alkaline
phosphatase, or horseradish peroxidase. Specific, non-limiting examples of
conjugating solutions include streptavidin alkaline phosphatase, avidin
alkaline
phosphatase, or horseradish peroxidase. The conjugated, hybridized complex can
be
15 treated with a detection reagent. In one example, the detection reagent
includes
enzyme-labeled fluorescence reagents or calorimetric reagents. In one specific
non-
limiting example, the detection reagent is enzyme-labeled fluorescence reagent
(ELF)
from Molecular Probes, Inc. (Eugene, OR). The hybridized complex can then be
placed on a detection device, such as an ultraviolet (UV) transilluminator
20 (manufactured by UVP, Inc. of Upland, CA). The signal is developed and the
increased signal intensity can be recorded with a recording device, such as a
charge
coupled device (CCD) camera (manufactured by Photometrics, Inc. of Tucson,
AZ).
In particular examples, these steps are not performed when radiolabels are
used.
In particular examples, the method further includes quantification, for
instance by
determining the amount of hybridization.
Allele Specific PCR
Allele-specific PCR differentiates between target regions differing in the
presence of
absence of a variation or polymorphism. PCR amplification primers are chosen
based
upon their complementarity to the target sequence, such as a sequence
disclosed
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41
herein. The primers bind only to certain alleles of the target sequence. This
method is
described by Gibbs, Nucleic Acid Res. 17:12427 2448, 1989.
Allele Specific Oligonucleotide Screening Methods
Further screening, methods employ the allele-specific oligonucleotide (ASO)
screening methods (e.g. see Saiki et al., Nature 324:163-166, 1986).
Oligonucleotides, with one or more base pair mismatches are generated for any
particular allele. ASO screening methods detect mismatches between one allele
in the
target genomic or PCR amplified DNA and the other allele, showing decreased
binding of the oligonucleotide relative to the second allele (i.e. the other
allele)
oligonucleotide. Oligonucleotide probes can be designed that under low
stringency
will bind to both polymorphic forms of the allele, but which at high
stringency, bind
to the allele to which they correspond. Alternatively, stringency conditions
can be
devised in which an essentially binary response is obtained, i.e., an ASO
corresponding to a variant form of the target gene will hybridize to that
allele, and not
to the wildtype allele.
Lipase Mediated Allele Detection Method
Ligase can also be used to detect point mutations, such as the SNPs in Table 3
in a
ligation amplification reaction (e.g. as described in Wu et al., Genomics
4:560-569,
1989). The ligation amplification reaction (LAR) utilizes amplification of
specific
DNA sequence using sequential rounds of template dependent ligation (e.g. as
described in Wu, supra, and Barany, Proc. Nat. Acad. Sci. 88:189-193, 1990).
Denaturing Gradient Gel Electrophoresis
Amplification products generated using the polymerase chain reaction can be
analyzed by the use of denaturing gradient gel electrophoresis. Different
alleles can be
identified based on the different sequence-dependent melting properties and
electrophoretic migration of DNA in solution. DNA molecules melt in segments,
termed melting domains, under conditions of increased temperature or
denaturation.
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Each melting domain melts cooperatively at a distinct, base-specific melting
temperature (Tm). Melting domains are at least 20 base pairs in length, and
can be up
to several hundred base pairs in length.
Differentiation between alleles based on sequence specific melting domain
differences
can be assessed using polyacrylamide gel electrophoresis, as described in
Chapter 7 of
Erlich, ed., PCR Technology, Principles and Applications for DNA
Amplification, W.
H. Freeman and Co., New York (1992).
Generally, a target region to be analyzed by denaturing gradient gel
electrophoresis is
amplified using PCR primers flanking the target region. The amplified PCR
product is
applied to a polyacrylamide gel with a linear denaturing gradient as described
in
Myers et at., Meth. Enzymol. 155:501-527, 1986, and Myers et al., in Genomic
Analysis, A Practical Approach, K. Davies Ed. IRL Press Limited, Oxford, pp.
95
139, 1988. The electrophoresis system is maintained at a temperature slightly
below
the Tm of the melting domains of the target sequences.
In an alternative method of denaturing gradient gel electrophoresis, the
target
sequences can be initially attached to a stretch of GC nucleotides, termed a
GC clamp,
as described in Chapter 7 of Erlich, supra. In one example, at least 80% of
the
nucleotides in the GC clamp are either guanine or cytosine. In another
example, the
GC clamp is at least 30 bases long. This method is particularly suited to
target
sequences with high Tm's.
Generally, the target region is amplified by the polymerase chain reaction as
described
above. One of the oligonucleotide PCR primers carries at its 5' end, the GC
clamp
region, at least 30 bases of the GC rich sequence, which is incorporated into
the 5' end
of the target region during amplification. The resulting amplified target
region is run
on an electrophoresis gel under denaturing gradient conditions as described
above.
DNA fragments differing by a single base change will migrate through the gel
to
different positions, which can be visualized by ethidium bromide staining.
Temperature Gradient Gel Electrophoresis
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Temperature gradient gel electrophoresis (TGGE) is based on the same
underlying
principles as denaturing gradient gel electrophoresis, except the denaturing
gradient is
produced by differences in temperature instead of differences in the
concentration of a
chemical denaturant. Standard TGGE utilizes an electrophoresis apparatus with
a
temperature gradient running along the electrophoresis path. As samples
migrate
through a gel with a uniform concentration of a chemical denaturant, they
encounter
increasing temperatures. An alternative method of TGGE, temporal temperature
gradient gel electrophoresis (TTGE or tTGGE) uses a steadily increasing
temperature
of the entire electrophoresis gel to achieve the same result. As. the samples
migrate
through the gel the temperature of the entire gel increases, leading the
samples to
encounter increasing temperature as they migrate through the gel. Preparation
of
samples, including PCR amplification with incorporation of a GC clamp, and
visualization of products are the same as for denaturing gradient gel
electrophoresis.
Single-Strand Conformation Polymorphism Analysis
Target sequences or alleles can be differentiated using single-strand
conformation
polymorphism analysis, which identifies base differences by alteration in
electrophoretic migration of single stranded PCR products, for example as
described
in Orita et al., Proc. Nat. Acad. Sci. 85:2766-2770, 1989. Amplified PCR
products can
be generated as described above, and heated or otherwise denatured, to form
single
stranded amplification products. Single-stranded nucleic acids can refold or
form
secondary structures which are partially dependent on the base sequence. Thus,
electrophoretic mobility of single-stranded amplification products can detect
base-
sequence difference between alleles or target sequences.
Chemical or Enzymatic Cleavage of Mismatches
Differences between target sequences can also be detected by differential
chemical
cleavage of mismatched base pairs, for example as described in Grompe et al.,
Am. J.
Hum. Genet. 48:212-222, 1991. In another method, differences between target
sequences can be detected by enzymatic cleavage of mismatched base pairs, as
described in Nelson et al., Nature Genetics 4:11-18, 1993. Briefly, genetic
material
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44
from an animal and an affected family member can be used to generate mismatch
free
heterohybrid DNA duplexes. As used herein, 'heterohybrid' means a DNA duplex
strand comprising one strand of DNA from one animal, and a second DNA strand
from another animal, usually an animal differing in the phenotype for the
trait of
interest.
Non-gel Systems
Other possible techniques include non-gel systems such as TagManTm (Perkin
Elmer).
In this system oligonucleotide PCR primers are designed that flank the
mutation in
question and allow PCR amplification of the region. A third oligonucleotide
probe is
then designed to hybridize to the region containing the base subject to change
between
different alleles of the gene. This probe is labeled with fluorescent dyes
at`.both the 5'
and 3' ends. These dyes are chosen such that while in this proximity to each
other the
fluorescence of one of them is quenched by the other and cannot be detected.
Extension by Taq DNA polymerase from the PCR primer positioned 5' on the
template relative to the probe leads to the cleavage of the dye attached to
the 5' end of
the annealed probe through the 5' nuclease activity of the Taq DNA polymerase.
This
removes the quenching effect allowing detection of the fluorescence from the
dye at
the 3' end of the probe. The discrimination between different DNA sequences
arises
through the fact that if the hybridization of the probe to the template
molecule is not
complete, i.e. there is a mismatch of some form, the cleavage of the dye does
not take
place. Thus only if the nucleotide sequence of the oligonucleotide probe is
completely
complimentary to the template molecule to which it is bound will quenching be
removed. A reaction mix can contain two different probe sequences each
designed
against different alleles that might be present thus allowing the detection of
both
alleles in one reaction.
Primer Design Strategy
Increased use of polymerase chain reaction (PCR) methods has stimulated the
development of many programs to aid in the design or selection of
oligonucleotides
used as primers for PCR. Four examples of such programs that are freely
available via
the Internet are: PRIMER by Mark Daly and Steve Lincoln of the Whitehead
Institute
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(UNIX, VMS, DOS, and Macintosh), Oligonucleotide Selection Program (OSP) by
Phil Green and LaDeana Hiller of Washington University in St. Louis (UNIX,
VMS,
DOS, and Macintosh), PGEN by Yoshi (DOS only), and Amplify by Bill Engels of
the University of Wisconsin (Macintosh only).
5
Generally these programs help in the design of PCR primers by searching for
bits of
known repeated-sequence elements and then optimizing the Tm by analyzing the
length and GC content of a putative primer. Commercial software is also
available 35
and primer selection procedures are rapidly being included in most general
sequence
10 analysis packages.
Designing oligonucleotides for use as either sequencing or PCR primers to
detect
requires selection of an appropriate sequence that specifically recognizes the
target,
and then testing the sequence to eliminate the possibility that the
oligonucleotide will
15 have a stable secondary structure. Inverted repeats in the sequence can be
identified
using a repeat-identification or RNA-folding programs.
If a possible stem structure is observed, the sequence of the primer can be
shifted a
few nucleotides in either direction to minimize the predicted secondary
structure.
When the amplified sequence is intended for subsequence cloning, the sequence
of the
oligonucleotide should also be compared with the sequences of both strands of
the
appropriate vector and insert DNA. Obviously, a sequencing primer should only
have
a single match to the target DNA. It is also advisable to exclude primers that
have
only a single mismatch with an undesired target DNA sequence. For PCR primers
used to amplify genomic DNA, the primer sequence should be compared to the
sequences in the GenBank database to determine if any significant matches
occur. If
the oligonucleotide sequence is present in any known DNA sequence or, more
importantly, in any known repetitive elements, the primer sequence should be
changed.
Embodiments of the present invention involve transformation of plants with a
polynucleotide according to the present invention. The polynucleotide may, for
example, be recovered from the cells of a natural host, or it may be
synthesized
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directly in vitro. Extraction from the natural host enables the isolation de
novo of
novel sequences, whereas in vitro DNA synthesis generally requires pre-
existing
sequence information. Direct chemical in vitro synthesis can be achieved by
sequential manual synthesis or by automated procedures. DNA sequences may also
be
constructed by standard techniques of annealing and ligating fragments, or by
other
methods known in the art. Examples of such cloning procedures are given in
Sambrook et al. (1989).
The polynucleotide may be isolated by direct cloning of segments of plant
genomic
DNA. Suitable segments of genomic DNA may be obtained by fragmentation using
restriction endonucleases, sonication, physical shearing, or other methods
known in
the art. A DNA sequence may be obtained by identification of a sequence' which
is
known to be expressed in a different organism, and then isolating the
homologous
coding sequence from an organism of choice. A coding sequence may be obtained
by
the isolation of messenger RNA (mRNA or polyA+ RNA) from plant tissue or
isolation of a protein and performing "back-translation" of its sequence. The
tissue
used for RNA isolation is selected on the basis that suitable gene coding
sequences
are believed to be expressed in that tissue at optimal levels for isolation.
Various methods for isolating mRNA from plant tissue are well known to those
skilled in the art, including for example using an oligo-dT oligonucleotide
immobilised on an inert matrix. The isolated mRNA may be used to produce its
complementary DNA sequence (cDNA) by use of the enzyme reverse transcriptase
(RT) or other enzymes having reverse trancriptase activity. Isolation of an
individual
cDNA sequence from a pool of cDNAs may be achieved by cloning into bacterial
or
viral vectors, or by employing the polymerase chain reaction (PCR) with
selected
oligonucleotide primers. The production and isolation of a specific cDNA from
mRNA may be achieved by a combination of the reverse transcription and PCR
steps
in a process known as RT-PCR.
Various methods may be employed to improve the efficiency of isolation of the
desired sequence through enrichment or selection methods including the
isolation and
comparison of mRNA (or the resulting single or double-stranded cDNA) from more
than one source in order to identify those sequences expressed predominantly
in the
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tissue of choice. Numerous methods of differential screening, hybridisation,
or
cloning are known to those skilled in the art including cDNA-AFLP, cascade
hybridisation, and commercial kits for selective or differential cloning.
The selected cDNA may then be used to evaluate the genomic features of its
gene of
origin, by use as a hybridisation probe in a Southern blot of plant genomic
DNA to
reveal the complexity of the genome with respect to that sequence.
Alternatively,
sequence information from the cDNA may be used to devise oligonucleotides and
these can be used in the same way as hybridisation probes; for PCR primers to
produce hybridisation probes, or for PCR primers to be used in direct genome
analysis.
Similarly the selected cDNA may be used to evaluate the expression profile of
its
gene of origin, by use as a hybridisation probe in a Northern blot of RNA
extracted
from various plant tissues, or from a developmental or temporal series. Again
sequence information from the cDNA may be used to devise oligonucleotides
which
can be used as hybridisation probes, to produce hybridisation probes, or
directly for
RT-PCR. The selected cDNA, or derived oligonucleotides, may then be used as a
hybridisation probe to challenge a library of cloned genomic DNA fragments and
identify overlapping DNA sequences.
In embodiments of the present invention, the polynucleotide according to the
present
invention may be coupled to a promoter which directs expression of SEQ ID NO
1, 2,
3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
24 or 25 or the
corresponding cDNA in the transgenic plant. The term "promoter" may be used to
refer to a region of DNA sequence located upstream of (i.e. 5' to) the gene
coding
sequence which is recognised by and bound by RNA polymerase in order for
transcription to be initiated.
In further embodiments of the present invention, the polynucleotide according
to the
present invention may be coupled to a promoter which directs expression of a
nucleotide sequence encoding the polypeptide of SEQ ID NO 26, 27, 28, 29, 30,
31,
32, 33, 34, 35, 36, 37, 38 or 39 in the transgenic plant.
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There are, broadly speaking, four types of promoters found in plant tissues;
constitutive, tissue-specific, developmentally-regulated, and
inducible/repressible,
although it should be understood that these types are not necessarily mutually
exclusive.
A constitutive promoter directs the expression of a gene throughout the
various parts
of a plant continuously during plant development, although the gene may not be
expressed at the same level in all cell types. Examples of known constitutive
promoters include those associated with the cauliflower mosaic virus 35S
transcript
(Odell et al, 1985), the rice actin 1 gene (Zhang et al, 1991) and the maize
ubiquitin 1
gene (Comejo et al, 1993). Constitutive promoters such as the Carnation Etched
Ring
Virus (CERV) promoter (Hull et al., 1986) are particularly preferred in the
present
invention.
A tissue-specific promoter is one which directs the expression of a gene in
one (or a
few) parts of a plant, usually throughout the lifetime of those plant parts.
The
category of tissue-specific promoter commonly also includes promoters whose
specificity is not absolute, i.e. they may also direct expression at a lower
level in
tissues other than the preferred tissue. Examples of tissue-specific promoters
known
in the art include those associated with the patatin gene expressed in potato
tuber and
the high molecular weight glutenin gene expressed in wheat, barley or maize
endosperm.
A developmentally-regulated promoter directs a change in the expression of a
gene in
one or more parts of a plant at a specific time during plant development. The
gene
may be expressed in that plant part at other times at a different (usually
lower) level,
and may also be expressed in other plant parts.
An inducible promoter is capable of directing the expression of a gene in
response to
an inducer. In the absence of the inducer the gene will not be expressed. The
inducer
may act directly upon the promoter sequence, or may act by counteracting the
effect
of a repressor molecule. The inducer may be a chemical agent such as a
metabolite, a
protein, a growth regulator, or a toxic element, a physiological stress such
as heat,
wounding, or osmotic pressure, or an indirect consequence of the action of a
pathogen
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or pest. A developmentally-regulated promoter might be described as a specific
type
of inducible promoter responding to an endogenous inducer produced by the
plant or
to an environmental stimulus at a particular point in the life cycle of the
plant.
Examples of known inducible promoters include those associated with wound
response, such as described by Warner et al (1993), temperature response as
disclosed
by Benfey & Chua (1989), and chemically induced, as described by Gatz (1995).
In certain embodiments of the present invention, the polynucleotide may be
transformed into plant cells leading to controlled expression under the
direction of a
promoter. The promoters may be obtained from different sources including
animals,
plants, fungi, bacteria, and viruses, and different promoters may work with
different
efficiencies in different tissues. Promoters may also be constructed
synthetically.
Exogenous genes/polynucleotides may be introduced into plants according to the
present invention by means of suitable plant transformation vectors. A plant
transformation vector may comprise an expression cassette comprising 5'-3' in
the
direction of transcription, a promoter sequence, a coding sequence comprising
SEQ
ID NO 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
21, 22, 23, 24
or 25 or the corresponding cDNA and, optionally a 3' untranslated, terminator
sequence including a stop signal for RNA polymerase and a polyadenylation
signal
for polyadenylase. Preferably the vector comprises a coding sequence
comprising a
nucleotide sequence encoding the polypeptide of SEQ ID NO 26, 27, 28, 29, 30,
31,
32, 33, 34, 35, 36, 37, 38 or 39. The promoter sequence may be present in one
or
more copies, and such copies may be identical or variants of a promoter
sequence as
described above. The terminator sequence may be obtained from plant, bacterial
or
viral genes. Suitable terminator sequences are the pea rbcS E9 terminator
sequence,
the nos terminator sequence derived from the nopaline synthase gene of
Agrobacterium tumefaciens and the 35S terminator sequence from cauliflower
mosaic
virus, for example. A person skilled in the art will be readily aware of other
suitable
terminator sequences.
The expression cassette may also comprise a gene expression enhancing
mechanism
to increase the strength of the promoter. An example of such an enhancer
element is
that derived from a portion of the promoter of the pea plastocyanin gene, and
which is
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the subject of International Patent Application No. WO 97/20056. These
regulatory
regions may be derived from the same gene as the promoter DNA sequence or may
be
derived from different genes, from Selex schwerinii, Selex viminalis or
Populus
trichocarpa or other organisms, for example from a plant of the family
Solanaceae, or
5 from the subfamily Cestroideae. All of the regulatory regions should be
capable of
operating in cells of the tissue to be transformed.
The promoter DNA sequence may be derived from the same gene as SEQ ID NO 1, 2,
3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
24 or 25 or the
10 corresponding cDNA used in the present invention or may be derived from a
different
gene.
The promoter DNA sequence may be derived from the same gene which comprises
the nucleotide sequence encoding the polypeptide of SEQ ID NO 26, 27, 28, 29,
30,
15 31, 32, 33, 34, 35, 36, 37, 38 or 39 used in the present invention or may
be derived
from a different gene.
The expression cassette may be incorporated into a basic plant transformation
vector,
such as pB1N 19 Plus, pBI 101, or other suitable plant transformation vectors
known
20 in the art. In addition to the expression cassette, the plant
transformation vector will
contain such sequences as are necessary for the transformation process. These
may
include the Agrobacterium vir genes, one or more T-DNA border sequences, and a
selectable marker or other means of identifying transgenic plant cells.
25 The term "plant transformation vector" means a construct capable of in vivo
or in vitro
expression. Preferably, the expression vector is incorporated in the genome of
the
organism. The term "incorporated" preferably covers stable incorporation into
the
genome.
30 Techniques for transforming plants are well known within the art and
include
Agrobacterium-mediated transformation, for example. The basic principle in the
construction of genetically modified plants is to insert genetic information
in the plant
genome so as to obtain a stable maintenance of the inserted genetic material.
A
review of the general techniques may be found in articles by Potrykus (Annu
Rev
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51
Plant Physiol Plant Mol Biol [1991] 42:205-225) and Christou (Agro-Food-
Industry
Hi-Tech March/April 1994 17-27).
Typically, in Agrobacterium-mediated transformation a binary vector carrying a
foreign DNA of interest, i.e. a chimaeric gene, is transferred from an
appropriate
Agrobacterium strain to a target plant by the co-cultivation of the
Agrobacterium with
explants from the target plant. Transformed plant tissue is then regenerated
on
selection media, which selection media comprises a selectable marker and plant
growth hormones. An alternative is the floral dip method (Clough & Bent, 1998)
whereby floral buds of an intact plant are brought into contact with a
suspension of
the Agrobacterium strain containing the chimeric gene, and following seed set,
transformed individuals are germinated and identified by growth on selective
media.
Direct infection of plant tissues by Agrobacterium is a simple technique which
has
been widely employed and which is described in Butcher D.N. et al., (1980),
Tissue
Culture Methods for Plant Pathologists, eds.: D.S. Ingrams and J.P. Helgeson,
203-
208.
Further suitable transformation methods include direct gene transfer into
protoplasts
using polyethylene glycol or electroporation techniques, particle bombardment,
micro-injection and the use of silicon carbide fibres for example.
Transforming plants using ballistic transformation, including the silicon
carbide
whisker technique are taught in Frame BR, Drayton PR, Bagnaall SV, Lewnau CJ,
Bullock WP, Wilson HM, Dunwell JM, Thompson JA & Wang K (1994). Production
of fertile transgenic maize plants by silicon carbide whisker-mediated
transformation
is taught in The Plant Journal 6: 941-948) and viral transformation techniques
is
taught in for example Meyer P, Heidmann I & Niedenhof I (1992). The use of
cassava
mosaic virus as a vector system for plants is taught in Gene 110: 213-217.
Further
teachings on plant transformation may be found in EP-A-0449375.
In a further aspect, the present invention relates to a vector system which
carries a
nucleotide sequence according to the present invention and introducing it into
the
genome of an organism, such as a plant. The vector system may comprise one
vector,
but it may comprise two vectors. In the case of two vectors, the vector system
is
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normally referred to as a binary vector system. Binary vector systems are
described in
further detail in Gynheung An et al., (1980), Binary Vectors, Plant Molecular
Biology
Manual A3, 1-19.
One extensively employed system for transformation of plant cells uses the Ti
plasmid from Agrobacterium tumefaciens or a Ri plasmid from Agrobacterium
rhizogenes An et al., (1986), Plant Physiol. 81, 301-305 and Butcher D.N. et
al.,
(1980), Tissue Culture Methods for Plant Pathologists, eds.: D.S. Ingrams and
J.P.
Helgeson, 203-208. After each introduction method of the desired exogenous
gene
according to the present invention in the plants, the presence and/or
insertion of
further DNA sequences may be necessary. If, for example, for the
transformation the
Ti- or Ri-plasmid of the plant cells is used, at least the right boundary and
often
however the right and the left boundary of the Ti- and Ri-plasmid T-DNA, as
flanking
areas of the introduced genes, can be connected. The use of T-DNA for the
transformation of plant cells has been intensively studied and is described in
EP-A-
120516; Hoekema, in: The Binary Plant Vector System Offset-drukkerij Kanters
B.B.,
Alblasserdam, 1985, Chapter V; Fraley, et al., Crit. Rev. Plant Sci., 4:1-46;
and An et
al., EMBO J. (1985) 4:277-284.
Plant cells transformed with nucleotides of the present invention may be grown
and
maintained in accordance with well-known tissue culturing methods such as by
culturing the cells in a suitable culture medium supplied with the necessary
growth
factors such as amino acids, plant hormones, vitamins, etc.
The "transgenic plant" in relation to the present invention may include any
plant that
comprises an exogenous polynucleotide/gene according to the present invention
or
any plant has been modified to up or down regulate expression of the
endogenous
gene/polynucleotide. Preferably the exogenous gene/polynucleotide is
incorporated in
the genome of the plant.
In one aspect, a nucleic acid sequence, plant transformation vector or plant
cell
according to the present invention is in an isolated form. The term "isolated"
means
that the sequence is at least substantially free from at least one other
component with
which the sequence is naturally associated in nature and as found in nature.
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In one aspect, a nucleic acid sequence, plant transformation vector or plant
cell
according to the invention is in a purified form. The term "purified" means in
a
relatively pure state - e.g. at least about 90% pure, or at least about 95%
pure or at
least about 98% pure.
The plants which are transformed with an exogenous gene according to the
present
invention include but are not limited to monocotyledonous and dicotyledonous
fodder
crops, forage crops, ornamental crops, fruit crops, food crops, algae,
forestry trees,
bioenergy crops and biofuel crops including the following species and species
hybrids: Acacia spp., Acer spp., Actinidia ssp., Agave spp., Agropyron spp.,
Agrostis
spp., Allium spp., Alnus spp., Alopecurus spp., Amaranthus spp., Ananas spp.,
Apium
spp., Arachis spp., Areca spp., Arundo spp., Arrhenatherum spp., Asparagus
spp;
Avena spp., Atriplex spp., Attalea spp., Beta spp., Betula spp., Brassica
spp., Bromus
spp., Bouteloua spp.,Camelina spp., Camellia spp., Cannabis spp., Capsicum
spp.,
Carica spp., Carex spp., Carthamus spp., Castanea spp., Carum spp., Cinnamomum
spp., Citrus spp., Cocos spp., Coffea spp., Corchorus spp., Cotoneatser spp.,
Cucurbita spp., Cupressus spp., Cynodon spp., Daucus spp., Dactylis spp.,
Eucalyptus
spp., Elaeis spp., Eleusine spp., Fagus spp., Festuca spp., Ficus spp.,
Fraxinus spp.,
Geranium spp., Ginkgo spp., Glycine spp., Gossypium spp., Helianthus spp.,
Hemerocallis spp., Heracleum spp., Hedysarum spp., Hibiscus spp., Hordeum
spp.,
Indigo spp., Ipomoea spp., Lettuca spp., Jatropha spp., Lotus spp., Lactuca
spp.,
Lathyrus spp., Lens spp., Linum spp., Lolium spp., Lupinus spp., Lezula spp.,
Lycopersicon spp., Malus spp., Manihot spp., Medicago spp., Melilotus spp.,
Mentha
spp., Miscanthus spp., Musa spp., Nicotiana spp., Olea spp., Onobrychis spp.,
Ophiopogon spp., Oryza spp., Panicum spp., Papaver spp., Petunia spp.,
Phaseolus
spp., Pennisetum spp., Phalaris spp., Phoenix spp., Phleum spp., Phyllostachys
spp.,
Physalis spp., Panicum spp., Picea spp., Pinus spp., Pistacia spp., Pisum
spp., Poa
spp., Podocarpus spp., Pogmania spp., Populus spp., Prunus spp., Quercus spp.,
Ribes spp., Robinia spp., Rosa spp., Raphanus spp., Rheum spp., Ricinus spp.,
Rubus
spp., Salix spp., Sequoia spp., Sesamum spp., Setaria spp., Saccharum spp.,
Sambucus
spp., Secale spp., Sinapis spp., Solanum spp., Sorghum spp., Trifolium spp.,
Triticum
spp., Triticosecale spp., Trisetum spp., Tagetes spp., Theobroma spp.,
Triadica spp.,
Vicia spp., Vitis spp., Vigna spp., Viola spp., Watsonia spp., Zea spp.
amongst others.
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Examples
Example 1
Plant material
This study focuses on the K8 willow mapping population. This population
comprises
947 full-sib individuals and was produced at Long Ashton Research Station
(LARS),
in 1999. The pedigree of the population is shown in Table 1.
Table 1
The K8 mapping population pedigree
Great great grandparents L810203 x L81102 L79069 X
Orm
(S. viminalis) (S. viminalis) (S. schwerini-) (S.
viminalis)
Great grandparents: SW880435 (var. Astrid) x SW910006 (var. Bjom)
(S. viminalis) (S. viminalis x S.
schwerini-)
Grandparents: SW880435 (var. Astrid) X SW 930984
(S. viminalis) (S. viminalis x S. schwerinii)
Parents:
S3 X R13
I
Progeny: K8 mapping population (947 individuals)
The population was established in a field experiment at LARS in 2000 and later
at
Rothamsted Research (RRes), Harpenden, Herts, UK in 2003. Six clonal
replicates of
each K8 genotype were planted as single plots, each in a 2 x 3 arrangement
within the
field experiment. Plots were arranged in a 52 x 23 plot row by column design.
To
facilitate identification of any environmental inconsistencies across the
trial site, and
to allow subsequent adjustment of trait values prior to QTL analyses, a
reference
willow variety was planted at 64 pre-selected plot positions throughout the
site. The
biomass cultivar, S. viminalis var. Jorr, was selected for this role at the
LARS site and
the cultivar Bowles Hybrid was used at RRes. These control genotypes were also
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used to surround the entire site to minimise any edge effects and also to form
internal
tramline columns after every fourth (RRes) or fifth (LARS) column of K8
progeny.
Progeny were arranged in random order in the design. For additional details,
see
Hanley SJ (2003) Genetic mapping of important agronomic traits in biomass
willow.
5 PhD thesis, University of Bristol, UK (Hanley, 2003).
Both plantations were established from 15 cm stem cuttings, allowed to grow
for one
year, after which the plants were coppiced during the winter by removing the
first
year's growth from the stool. Plants were then allowed to grow for a further
two
10 years before a second cutback. Plants were then coppiced after each period
of three
seasons of growth.
Trait measurements
Trait measurements were made according to Table 2 below.
Table 2
'single stem' 'multi stem'
Trait measured Nursery Establishment 1st year post 2nd year 1st year post 2nd
year 3rd year post
year cutback post cutback cutback post cutback
cutback
Biomass Yield - TARS - LARS,RRes - - LARS,RRest
Maximum stem LARS LARS LARS LARS,RRes - - LARS,RRest
height
Mean stem height - LARS LARS LARS,RRes - - LARS,RRest
Maximum stem - LARS LARS,RRes' LARS,RRes - - LARS,RRest
diametert
Mean stem
diameter
Shoot no.per stool - LARS LARS LARS,RRes - - LARS,RRest
% Moisture - LARS - LARS,RRes - - LARS,RRest
content
Rust resistance - LARS LARS LARS - - -
trait measured on 480 progeny only
t: RRes data available Spring 2008 1 cutback 2" cutback 3` cutback
t: stem diameters measured at 55cm from the stool
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Trait data was first analysed for spatial inconsistencies across the trial
site and data
adjusted to account for this. The method of Residual Maximum Likelihood (REML)
(Patterson and Thompson 1971; Robinson et al. 1982) was used to fit mixed
(involving fixed and random effects) models (Searle et al. 1992) to the trait
data,
employing GenStat software ((DSixth Edition, Lawes Agricultural Trust,
Rothamsted
Experimental Station, 2002). Using theory developed by Gleeson and Cullis
(1987),
Cullis and Gleeson (1991) and Cullis et al. (1998), the most appropriate model
to
correctly describe the effects of spatial trends, defined as autoregressive
components
for rows and or columns, for data from each assessment was identified. This
utilised
the trait information provided by a reference genotypes (Jorr or Bowles
Hybrid).
Changes in model deviance (Genstat Committee 1993) were used to assess the
significance (P < 0.05) of any extra (spatial) terms in models, these changes
being
asymptotically distributed as chi-squared on degrees of freedom equal to the
number
of extra parameters.
Adjusted trait scores were then utilised in QTL analysis according to standard
methodologies as included in the software package MapQTL (Kyazma).
Identification and high resolution mapping of the yield QTL
The yield QTL was first identified following an initial QTL screen based on K8
progeny numbers 1- 480 only. The K8 linkage map comprised amplified fragment
length polymorphism (AFLP) and microsatellite markers. In addition, a genome-
wide
set of Single Nucleotide Polymorphism (SNP) markers was developed and included
in
analysis for aligning the K8 willow map to the publicly-available poplar
genome
sequence. Further details of this approach are available in Hanley, S.J.,
Mallott, M.D.
& Karp A. (2006) Tree Genetics and Genomes, 3, 35-48
Once the approximate position of the QTL was determined (on Linkage Group X;
Linkage group nomenclature is a provided for the poplar genome sequence ;
http://genome.jgi-psf.org/Poptrl_I/Poptrl_l.home.html) through the initial QTL
screen, an additional 11 SNP markers were developed to target this region to
increase
mapping resolution and further delimit the locus. The SNP markers were derived
from sequencing willow orthologues of genes in this region of the poplar
genome
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57
sequence. Full details of the method developed for identifying SNP markers are
described in Hanley, S.J., Mallott, M.D. & Karp A. (2006) Tree Genetics and
Genomes, 3, 35-48.
Forward PCR Reverse PCR primer
Marker Class primert5'-+3') (5'-+3') SNapShot primer Type
X_15341094 SNP GGGAAACAGATAGTGGGCAGTC GCCTCCTTCTCCTGTAAGCAC
ACCTTAACCTGCAGCTCTTACCTTAA ACxAC
X_15478832 SNP TGATGCCTCCAAAGGTTTCTC TCCTGGCGTGTTCATAGAGGT
GATGGGAAGTAAAAATTATCCGAGCAAGAT ACxAC
X_15533399 SNP GTGGCTCTTCTCCATTGCTGT GTGCTTTTTGCTCCACCTTTG
AATAGCAAATATGGGGGCTT ATxAT
X_15727779 SNP AGAAGGGATGTGCCAAAGTGA ACAAGCTGGATTGGTGGAAGA
ACTTTTGATATTTTCTAACCTTTTCTCTTATTGTA CTxCT
5758822 SSR CAAAAACGCACCCTATTCTFCC CCAGAGTCCCCTTGAACACAC - abxac
X_15777280 SNP AAAACAACCTCCCTCCCTTGA TCTGCAAGCCCACTTTTTCTT
TTTGAGGAAGACGGCAAATG TGxTG
X_15905315 SNP CAACATATTGTGGATGCAG9a CAGTGATACAATGTCTGCAAGGA
AGGATTTCCCACAGATTGGTTTCAC CGxCG
X_15917077 SNP TTCCTTGTTTTGGCTTTGGTG CCATCGCCTGTATCCACACTT
ATTCAGCTGTCGAATTGATTGATT TGxTG
X15951166 SNP TGGTGAGCGAGAGTACGTGAA AA TCTTCCTGGCCCTCAAAAC GGGTATGCTCAGCCTGCC
ACxAC
X15945623 SNP ATTGGAATCTCTTGGGGCTTT CACCTGCTCCATAATCCCTCT
TCATTGATAACTGCTATTGTTCCCCAGA AGxAG
X15958515 SNP CAGAGACCCAAATGGACTGGA AACGACCTAATCCCCTGGAAA
TCAATGCATGACGGTGTTCTTGTGGTGACAGT AGxAG
It should be noted that the marker numbers do not necessarily refer to the
most up
date position available in the poplar genome and this may change due to
ongoing
annotation and assembly.
All of these SNP markers were heterozygous in both mapping population parents
(S3
& R13) and segregated according to the expected 1:2:1 (AA:AB:BB) ratio in the
progeny. All 11 markers were used to genotype the 947 individuals of the
mapping
population. Forty three individuals were not included in subsequent analysis
as
genotyping failed in some instances and some plants had died in the field and
DNA
for screening was no longer available. A fine-scale linkage map was then
calculated
based on the 11 markers. The order of markers on the willow map is co-linear
with
the poplar genome sequence.
The resulting linkage map spanned 5.1 cM. This map was used in conjunction
with
the genotype and trait data in a second round of QTL analysis. Results of
interval
mapping are shown in Fig. 13 for total fresh weight for two harvest years at
the LARS
site (2003 & 2006) and for the RRes site in 2005. QTL for maximum stem
diameter
and maximum stem height are also shown for both sites for equivalent years.
These
traits are highly correlated with total harvestable yield in this population
(Hanley SJ
(2003) Genetic mapping of important agronomic traits in biomass willow. PhD
thesis,
University of Bristol, UK).
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The sequences for willow markers X 15341094, X15758822, X15905315 and
X15958515 also yielded SNPs that were specific to each parent indicating that
there
are three haplotypes segregating in this region in the K8 population. Due to
the nature
of the cross that generated the K8 population, there is a maximum of three
alleles
segregating at any given locus in this population. As explained in Example 2,
the
female parent of the cross, cultivar `S3' was found to produce two alleles of
different
length (A & B). The male parent, cultivar 'R13' was found to contain two
alleles (A
& C) where A is a common allele that is present in S3. The diploid K8 mapping
population can therefore inherit the following combinations of alleles : AA,
AB, AC,
BC. As indicated in Example 2, allele C is associated with increased
harvestable
biomass yield when compared to the contribution of allele A to harvestable
biomass
yield.
Sequence analysis of the QTL region based on the poplar genome.
QTL indicates that the most likely position of the QTL is between markers
X15727779 and X15917077. The position of these markers in the poplar genome
was determined by BLASTN homology searches using the willow sequence used to
derive the SNP markers.
The homologous genomic region in poplar is predicted to contain 10 genes.
These are
referred to as Xyldl, Xyld2, Xyld3, Xyld4, Xyld5, Xyld6, Xyld7, Xyld8, Xyld9
and
XyldlO. The physical size of this region is predicted to be 196118 base pairs
in
length. However, a gap in the public sequence prevents an accurate measure of
the
length. Eight of the genes have EST sequence to support their expression.
Two willow BAC clones have been identified that cover the region delimited by
the
two markers. Partial sequencing of these clones indicates that homologues to 9
of the
10 genes within the QTL region in poplar can be identified in willow plant
'R13'.
`R13' contains two alleles (A and C) and Figure 2 shows the sequence of the
QTL
region of allele A. Alleles A and C of the 9 willow genes were identified
using
routine techniques and are shown in the Figures.
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The amino acid sequences of the polypeptides encoded by Alleles A and C of the
9
willow genes are shown in the Figures. These were identified using cDNA
sequences
that allowed exons in the gene sequences to be identified and thus the
polypeptide
sequence to be predicted. The cDNA sequences were predicted by full sequencing
of
salix transcripts that allowed intron-exon boundaries to be identified. In
some cases
the exons were predicted using annotation information on the public poplar
genome
website. These predictions are based on transcript sequencing in poplar and
gene
prediction algorithms. Polypeptide sequences were predicted using partially
sequenced willow transcripts in conjunction with public poplar genome
annotation
data which is based on gene finding algorithms and poplar transcript sequence
information (Tuskan et al., 2006. The Genome of Black Cottonwood, Populus
trichocarpa (Torr. & Gray) Science 313 p5793."
Details of the genes are detailed below:
1. Xyldl
Shows best homology in Arabidopsis thaliana with Locus AT3G12740, or ALISI
(ALA-Interacting Subunit). ALIS 1 is a member of a family of phospholipid
transporters (ALIS 1 -ALIS5) which are hoinologs of the Cdc50p/Lem3p family in
yeast that are essential for the trafficking of yeast P4-ATPases. The
Arabidopsis ALIS
proteins are 27-30% identical to yeast Cdc50p and similarity ranges from 48-
53%. In
yeast ALIS 1 shows strong affinity to ALA3. In Arabidopsis, ALA3 has been
shown
to be important for trans-Golgi proliferation of slime vesicles containing
polysaccharides and enzymes for secretion. In yeast, ALAS function requires
interaction with the ALIS1. In Arabidopsis plants, ALISI, like ALA3, is
localised to
membranes of Golgi-like structures and is expressed in root peripheral
columella
cells. It has been proposed that the ALIS1 protein is a (3- sub-unit of ALA3
in
Arabidopsis and that this protein is important part of the Golgi machinery in
plants
required for secretory processes during development.
Relevant publications
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Poulsen LR, Lopez-Marques RL, McDowell SC, Okkeri J, Licht D, Schulz A,
Pomorski T, Harper JF, Palmgren MG. 2008 The Arabidopsis P4-ATPase ALA3
localizes to the golgi and requires a beta-subunit to function in lipid
translocation and
secretory vesicle formation. Plant Cell. 3:658-76.
5
Bosco CD, Lezhneva L, Biehl A, Leister D, Strotmann H, Wanner G, Meurer J.
2004
Inactivation of the chloroplast ATP synthase gamma subunit results in high non-
photochemical fluorescence quenching and altered nuclear gene expression in
Arabidopsis thaliana. J Biol Chem.279(2):1060-9.
2. Xyld 2
Shows strongest homology to Arabidopsis thaliana gene ALDH5F1 (Locus
AT1G79440 ; previous nomenclature SSADH; EC 1.2.1.24) which is a member of the
aldehyde dehydrogenases (ALDHs) protein superfamily of NAD(P)C-dependent
enzymes that oxidize a wide range of endogenous and exogenous aliphatic and
aromatic aldehydes. The Arabidopsis genome contains 14 unique ALDH sequences
encoding members of nine ALDH families, including eight known families and one
novel family (ALDH22) that is currently known only in plants. Of these,
there is one succinic semialdehyde dehydrogenase gene, ALDH5FJ, which encodes
a
protein of 528 amino acids. ALDH5F1 is the only confirmed identified member of
the
succinic semialdehyde family in plants. The Arabidopsis protein is localized
to
mitochondria and a kinetic analysis showed that the recombinant enzyme was
specific
for succinic semialdehyde and regulated by adenine nucleotides. T-DNA knockout
mutants of ALDH5FJ result in dwarfed plants with necrotic lesions and are
sensitive
to both ultraviolet-B light and heat stress. Plants with ssadh mutations
accumulate
elevated levels of H202, suggesting a role for this gene in stress regulation
detoxification pathway plant, providing defense against environmental stress
by
preventing the accumulation of reactive oxygen species.
Relevant publications
Hueser, AF, Ul L. 2008 Analysis of GABA-shunt metabolites in Arabidopsis
thaliana
19th International Conference on Arabidopsis Research
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61
Ludewig F, HUser A, Fromm H, Beauclair L, Bouche N. 2008 Mutants of GABA
transaminase (POP2) suppress the severe phenotype of succinic semialdehyde
dehydrogenase (ssadh) mutants in Arabidopsis. PLoS ONE 3(10):e3383
Zybailov B, Rutschow H, Friso G, Rudella A, Emanuelsson 0, Sun Q, van Wijk KJ.
2008 Sorting signals, N-terminal modifications and abundance of the
chloroplast
proteome. PLoS ONE 3(4):e1994
Fait A, Yellin A, Fromm H. 2005 GABA shunt deficiencies and accumulation of
reactive oxygen intermediates: insight from Arabidopsis mutants. FEBS Lett.
579(2):415-20
Kirch HH, Bartels D, Wei Y, Schnable PS, Wood AJ. 2004 The ALDH gene
superfamily of Arabidopsis. Trends Plant Sci. 9(8):371-7
Breitkreuz KE, Allan WL, Van Cauwenberghe OR, Jakobs C, Talibi D, Andre B,
Shelp BJ. 2003 A novel gamma-hydroxybutyrate dehydrogenase: identification and
expression of an Arabidopsis cDNA and potential role under oxygen deficiency.
J
Biol Chem. 278(42):41552-6.
3. XyId3
Shows strongest homology with Arabidopsis thaliana ALTERED PHLOEM
DEVELOPMENT (APL) gene (Locus AT1G79430), which encodes a MYB coiled-
coil-type transcription factor that is required for phloem identity in
Arabidopsis. APL
has been proposed to have a dual role both in promoting phloem differentiation
and in
repressing xylem differentiation during vascular development.
Relevant publications
Truernit E, Bauby H, Dubreucq B, Grandjean 0, Runions J, Barthelemy J,
Palauqui
JC. 2008 High-resolution whole-mount imaging of three-dimensional tissue
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62
organization and gene expression enables the study of Phloem development and
structure in Arabidopsis. Plant Cell. 20(6):1494-503
Lehesranta S, Lindgren 0, Taehtiharju S, Carlsbecker A, Helariutta Y 2008 The
role
of APL as a transcriptional regulator in specifying vascular identity 19th
International
Conference on Arabidopsis Research
Carlsbecker A, Lindgren 0, Bonke M, Thitamadee S, Tahtiharju S, Helariutta Y
2004
Genetic analysis of procambial development in the Arabidopsis root 15th
International Conference on Arabidopsis Research
Bonke M, Hauser M-T, Helariutta Y 2002 The APL locus is required for phloem
development in Arabidopsis roots. 13th International Conference on Arabidopsis
Research
4. Xyld4
Show strongest homology in Arabidopsis thaliana to Locus AT1G79420. Function
not yet described.
5. Xyld5
Shows strongest homology with AtOCT2 in Arabidopsis thaliana (Locus
AT1G79360). ATOCT2 is one of six Arabidopsis organic cation/carnitine
transporter
(OCT) -like proteins, named AtOCTI-AtOCT6 (loci At1g73220, At1g79360,
Atlg16390, At3g20660, At1g79410 and At1g16370, respectively) that have been
identified. These proteins cluster in a small subfamily within the `organic
solute
cotransporters' included in the large sugar transporter family of the major
facilitator
superfamily (MFS). AtOCTI shares features of organic cation/camitine
transporters
(OCTs). In animals, mammalian plasma membrane OCTs are involved in homeostasis
and distribution of various small endogenous amines (e.g. carnitine, choline)
and
detoxification of xenobiotics such as nicotine. AtOCTI is able to transport
carnitine in
yeast and is likely to be involved in the transport of carnitine or related
molecules
across the plasma membrane in plants.
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The orthologous gene sequence has not yet been identified in willow.
Related publication
Tohge T, Nishiyama Y, Hirai MY, Yano M, Nakajima J, Awazuhara M, Inoue E,
Takahashi H, Goodenowe DB, Kitayama M, Noji M, Yamazaki M, Saito K. 2005
Functional genomics by integrated analysis of metabolome and transcriptome of
Arabidopsis plants over-expressing an MYB transcription factor. Plant J.
42(2):218-
35
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64
6. XyId6
Shows best fit with ATOCT3 Arabidopsis ORGANIC CATION/CARNITINE
TRANSPORTER2). ATOCT3 is one of six Arabidopsis organic cation/carnitine
transporter (OCT) -like proteins, named AtOCTI-AtOCT6 (loci At1g73220,
At]g79360, At1g16390, At3g20660, At]g79410 and Atig16370, respectively)
referred to above. These proteins cluster in a small subfamily within the
`organic
solute cotransporters' included in the large sugar transporter family of the
major
facilitator superfamily (MFS).
Relevant publications
Lelandais-Briere C, Jovanovic M, Torres GA, Perrin Y, Lemoine R, Corre-Menguy
F,
Hartmann C. 2007 Disruption of AtOCTI, an organic cation transporter gene,
affects
root development and carnitine-related responses in Arabidopsis. Plant J.
51(2):154-
64
Price J, Laxmi A, St Martin SK, Jang JC. 2004 Global transcription profiling
reveals
multiple sugar signal transduction mechanisms in Arabidopsis. Plant Cell.
16(8):2128-
50
7. Xy1d7
Shows homology with members of the R2R3-type MYB gene family in Arabidopsis.
Although no functional data are available for most of the 125 R2R3-type AtMYB
genes, a number of functions have been assigned concerning many aspects of
plant
secondary metabolism, as well as the identity and fate of plant cells. This
includes
regulation of phenylpropanoid metabolism, control of development and
determination
of cell fate and identity, plant responses to environmental factors and
mediating
hormone actions.
Relevant publications
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Stracke R, Werber M, Weisshaar B. 2001 The R2R3-MYB gene family in
Arabidopsis thaliana. Curr Opin Plant Biol. 4(5):447-56
Riechmann JL, Heard J, Martin G, Reuber L, Jiang C, Keddie J, Adam L, Pineda
0,
5 Ratcliffe OJ, Samaha RR, Creelman R, Pilgrim M, Broun P, Zhang JZ,
Ghandehari D,
Sherman BK, Yu G. 2000 Arabidopsis transcription factors: genome-wide
comparative analysis among eukaryotes. Science. 290(5499):2105-10
8. Xyld8
Shows best fit with ANAC028, Arabidopsis NAC domain containing protein (Locus
AT1 G65910). NAC (NAM, ATAF, and CUC) is a plant-specific gene family. NAC
-family transcription factors are involved in maintaining organ or tissue
boundaries
regulating the transition from growth by cell division to growth by cell
expansion.
Most NAC proteins contain a highly conserved N-terminal DNA-binding domain, a
nuclear localization signal sequence, and a variable C-terminal domain. 75 and
105
NAC genes were predicted in the Oryza sativa and Arabidopsis genomes,
respectively. The functions of only some of these have been described. The
first
reported NAC genes were NAM from petunia and CUC2 from Arabidopsis that
participate in shoot apical meristem development. CUCI, CUC2 and nam are
expressed at the boundaries between cotyledonary primordial and between floral
organs and are specifically involved in shoot apical meristem formation and
separation of cotyledons and floral organs. Other development-related NAC
genes
have been suggested with roles in controlling cell expansion of specific
flower organs
e.g. NAP or auxindependent formation of the lateral root system e.g. NACI.
Some of
NAC genes, such as ATAF1 and ATAF2 genes from Arabidopsis and the StNAC gene
from potato, are induced by pathogen attack and wounding. More recently, a few
NAC
genes, such as AtNAC072 (RD26), AtNAC019, AtNAC055 from Arabidopsis, and
BnNAC from Brassica (31), were found to be involved in responses to
environmental
stress. Seven members of NAC family At2g18060, At4g36160, At5g66300,
Atlg12260, At1g62700, At5g62380, and At1g71930 have been designated as
VASCULAR-RELATED NAC-DOMAIN PROTEIN 1 (VNDI to VND7). Members of
these could induce transdifferentiation of various cells into metaxylem- and
protoxylem-like vessel elements, respectively, in Arabidopsis and poplar.
Similarly
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ANAC012 and ANAC073 also appear to have a role in xylem development and
secondary wall thickening in Arabidopis.
Relevant publications
Ooka H, Satoh K, Doi K, Nagata T, Otomo Y, Murakami K, Matsubara K, Osato N,
Kawai J, Caminci P, Hayashizaki Y, Suzuki K, Kojima K, Takahara Y, Yamamoto K,
Kikuchi S. 2003 Comprehensive analysis of NAC family genes in Oryza sativa and
Arabidopsis thaliana. DNA Res. 10(6):239-47
Riechmann JL, Heard J, Martin G, Reuber L, Jiang C, Keddie J, Adam L, Pineda
0,
Ratcliffe OJ, Samaha RR, Creelman R, Pilgrim M, Broun P, Zhang JZ, Ghandehari
D,
Sherman BK, Yu G. 2000 Arabidopsis transcription factors: genome-wide
comparative analysis among eukaryotes. Science 290(5499):2105-109.
Xyld9
Show strongest homology in Arabidopsis thaliana to Locus AT1G79390. The
function of this expressed protein has not yet been described
10. XyId10
Shows homology to the RGLG2 (RING DOMAIN LIGASE2) locus of Arabidopsis
thaliana (Locus AT1G79380). In functional terms, the RING domain can basically
be
considered a protein-interaction domain. RING-forger proteins have been
implicated
in a range of diverse biological processes and biochemical activities, from
transcriptional and translational regulation to targeted protein degradation.
Relevant publications
Kosarev P, Mayer KF, Hardtke CS. 2002 Evaluation and classification of RING-
finger domains encoded by the Arabidopsis genome. Genome Biol. 3(4):RESEARCH
0016.1
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Example 2
Provided below is an example of the use of a diagnostic molecular marker
derived
from the QTL region that can be used to select for favourable alleles within a
breeding
programme:
A microsatellite marker was developed to screen for the three QTL alleles
segregating
in members of the K8 population of Salix. The microsatellite marker is
amplified by
PCR using the following pair of primers:
Forward primer 5'- CAAAAACGCACCCTATTCTTCC - 3'
Reverse primer 5'- CCAGAGTCCCCTTGAACACAC - 3'
The sequence of the amplified region for allele A (179bp) is:
CAAAAACGCACCCTATTCTTCCCTATTTGCATCGCATTTGTTCTTGAATCTC
TTTGTATTCCCTGAGTCTCAGAGAGAGAGAGAGAGAGAGAGAGAAGGAA
AGAGAGAATGTTCCATACCAAGAAACCCTCAACTATGAATTCCCATGATA
GACCCATGTGTGTTCAAGGGGACTCTGG
These primers generate amplicons of three different lengths in the K8 mapping
population and thus are informative for the three alleles that are segregating
in the
yield QTL region. The female parent of the cross, cultivar `S3' produces two
alleles
of different length (A & B). The male parent, cultivar `R13' contains two
alleles (A
& C) where A is a common allele that is present in S3.
The diploid K8 mapping population can therefore inherit the following
combinations
of alleles : AA, AB, AC, BC. Table 3 shows the mean trait values for each of
these
classes in the population for total fresh weight harvested, maximum stem
diameter
and maximum stem height. Analysis is based trait data collected at Long Ashton
Research Station in 2003. The non-parametric rank-sum test of Kruskal-Wallis
(KW)
(Lehmann, 1975) was used to determine associations between marker genotypes
and
trait scores.
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Table 3. Mean trait values associated with inheritance of particular QTL
alleles (A, B
and C) in the K8 mapping population as determined by the application of a
microsatellite marker.
Trait N microsatellite genotype KW df Significance
AA AB AC BC
Total fresh biomass harvested per
stool (kg) 902 1.30 1.90 1.75 2.17 132.76 3 *******
Maximum stem diameter per stool
(cm) 849 16.30 20.12 19.22 21.37 186.37 3 *******
Maximum stem height per stool
(m) 902 3.16 3.79 3.69 3.96 223.95 3 *******
N : Number of plants included in analysis
KW: Kruskal-Wallis test statistic
df : degrees of freedom
Significance: ******* = 0.0001
In this example, plants of genotype AA often give the lowest yield and plants
of
genotype BC often give rise to the highest yields. Where the goal of a
breeding
programme is to increase harvestable biomass yield, plants of genotype BC
would be
preferentially selected using the marker. Similarly, potential parents of
genotype AA
might be excluded from a crossing programme as this allele can be associated
with
lower yields.
Example 3
Disruption of Xyld7 gene sequence in QTL haplotype A
An alignment of Gene Xyld7 allele A (SEQ ID NO 2) sequence with the Gene Xyld7
allele C sequence (SEQ ID NO 1) (as shown in the alignment of Figure 9D)
indicates
Gene Xyld7 allele A has an insertion region with extra nucleotides that are
not present
in Gene Xyld7 allele C sequence SEQ ID NO 1. SEQ ID NO 26 (as shown in Figure
9E) shows the amino acid sequence of the Salix Xyld7 allele C polypeptide.
A comparison of Xyld7 gene sequences for both alleles of plant R13 (alleles A
and C)
identified an insertion in Xyld7 A allele which is not present in the Xyld_C
allele
sequence. To determine whether the insertion is in coding sequence, the
transcript of
allele C of this gene was fully sequenced which confirmed that the insertion
in allele
A is within exon 3 of the gene. The resulting allele A transcript, if
expressed, would
CA 02748665 2011-06-30
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69
not be expected to encode a functional protein. Indeed, while both allele B
and C
transcripts have been identified, no allele A derived transcript has yet been
identified
in plants S3 and R13 (the K8 parents which carry either the A and B alleles or
the A
and C alleles, respectively). It is therefore possible that allele A of this
gene is non-
functional in the K8 mapping population and this may contribute to the
underlying
phenotypic variation that is represented by the biomass yield QTL.
All publications mentioned in the above specification are herein incorporated
by
reference. Various modifications and variations of the described methods and
system
of the invention will be apparent to those skilled in the art without
departing from the
scope and spirit of the invention. Although the invention has been described
in
connection with specific preferred embodiments, it should be understood that
the
invention as claimed should not be unduly limited to such specific
embodiments.
Indeed, various modifications of the described modes for carrying out the
invention
which are apparent to those skilled in molecular biology or related fields are
intended
to be within the scope of the following claims.
